2528 lines
		
	
	
		
			41 KiB
		
	
	
	
		
			Plaintext
		
	
	
		
		
			
		
	
	
			2528 lines
		
	
	
		
			41 KiB
		
	
	
	
		
			Plaintext
		
	
	
|  | #LyX 2.0 created this file. For more info see http://www.lyx.org/ | ||
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 | ||
|  | \begin_layout Section | ||
|  | Introduction | ||
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|  | 
 | ||
|  | \begin_layout Standard | ||
|  | This document describes the coordinate frame conventions in which GTSAM | ||
|  |  inputs and represents states and uncertainties. | ||
|  |  When specifying initial conditions, measurements and their uncertainties, | ||
|  |  and interpreting estimated uncertainties and the results of geometry operations | ||
|  | , the coordinate frame convention comes into play. | ||
|  | \end_layout | ||
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 | ||
|  | \begin_layout Standard | ||
|  | GTSAM as consistently as possible represents all states and uncertainties | ||
|  |  in the body frame. | ||
|  |  In cases where several frames are used simultaneously, a good rule of thumb | ||
|  |  is that measurements and uncertainties will be represented in the  | ||
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 | ||
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|  | Frame Conventions in Geometry, Lie Group, and Manifold Operations | ||
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|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a.\mathbf{logmap}()==\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell multicolumn="1" alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | \begin_inset space \quad{} | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Lie group actions | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell multicolumn="2" alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell multicolumn="2" alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell multicolumn="2" alignment="center" valignment="top" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $q=a.\mathbf{transform\_to}\left(p\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $q=p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $q=a^{-1}p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $q=a.\mathbf{transform\_from}\left(p\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $q=a\mathbf{*}p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $q=p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $q=ap$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | </lyxtabular> | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \begin_inset Caption | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \begin_inset CommandInset label | ||
|  | LatexCommand label | ||
|  | name "tab:Coordinate-frame-transformations" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Coordinate frame transformations performed by GTSAM geometry operations. | ||
|  |  Here,  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | ,  | ||
|  | \begin_inset Formula $b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | ,  | ||
|  | \begin_inset Formula $c$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , and  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  are Lie group elements (Pose2, Pose3, Rot2, Rot3, Point2, Point3,  | ||
|  | \emph on | ||
|  | etc | ||
|  | \emph default | ||
|  | ). | ||
|  |   | ||
|  | \begin_inset Formula $\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a set of Lie algebra coordinates (i.e. | ||
|  |  linear update, linear delta, tangent space coordinates), and  | ||
|  | \begin_inset Formula $\mathrm{X}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a Lie group type (e.g. | ||
|  |  Pose2). | ||
|  |   | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  and  | ||
|  | \begin_inset Formula $q$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  are the objects of Lie group actions (Point2, Point3,  | ||
|  | \emph on | ||
|  | etc | ||
|  | \emph default | ||
|  | ). | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | At the core of most coordinate frame usage in GTSAM are geometry and Lie | ||
|  |  group operations. | ||
|  |  We explain the geometry and Lie group operations in GTSAM in terms of the | ||
|  |  coordinate frame transformations they perform, detailed in Table | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset CommandInset ref | ||
|  | LatexCommand ref | ||
|  | reference "tab:Coordinate-frame-transformations" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | \begin_inset Float table | ||
|  | wide false | ||
|  | sideways false | ||
|  | status open | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \align center | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Tabular | ||
|  | <lyxtabular version="3" rows="3" columns="4"> | ||
|  | <features booktabs="true" tabularvalignment="middle"> | ||
|  | <column alignment="left" valignment="top" width="4.5cm"> | ||
|  | <column alignment="left" valignment="top" width="1cm"> | ||
|  | <column alignment="left" valignment="top" width="1.25cm"> | ||
|  | <column alignment="left" valignment="top" width="3.75cm"> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | Syntax | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | Input | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | Output | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | Identities | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $\delta=a.\mathbf{localCoordinates}\left(b\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a.\mathbf{retract}\left(\delta\right)==b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\mathbf{I}.\mathbf{localCoordinates}($ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\quad a.\mathbf{between}\left(b\right))==\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $b=a.\mathbf{retract}\left(\delta\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $a.\mathbf{compose}($ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\quad\mathbf{I}.\mathbf{retract}\left(\delta\right))==b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | </lyxtabular> | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \begin_inset Caption | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \begin_inset CommandInset label | ||
|  | LatexCommand label | ||
|  | name "tab:Coordinate-frames-manifold" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Coordinate frames for manifold tangent space operations. | ||
|  |  Here,  | ||
|  | \begin_inset Formula $a$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | ,  | ||
|  | \begin_inset Formula $b$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , and  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  are manifold elements,  | ||
|  | \begin_inset Formula $\delta$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a tangent space element, and  | ||
|  | \begin_inset Formula $\mathrm{X}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a Lie group type (e.g. | ||
|  |  Pose2). | ||
|  |  For the identities column, we assume the elements are also Lie group elements | ||
|  |  with identity  | ||
|  | \begin_inset Formula $\mathbf{I}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | The manifold tangent space operations  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | retract | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  and  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | local coordinates | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  also work in the body frame for Lie group elements. | ||
|  |  The tangent space coordinates given to  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | retract | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  should be in the body frame, not the global frame. | ||
|  |  Similarly, the tangent space coordinates returned by  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | local coordinates | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  will be in the same body frame. | ||
|  |  This is detailed in Table | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset CommandInset ref | ||
|  | LatexCommand ref | ||
|  | reference "tab:Coordinate-frames-manifold" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Section | ||
|  | Frame and Uncertainty Conventions For Built-in Factors | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | \begin_inset Float table | ||
|  | wide false | ||
|  | sideways false | ||
|  | status open | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | \align center | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Tabular | ||
|  | <lyxtabular version="3" rows="7" columns="5"> | ||
|  | <features tabularvalignment="middle"> | ||
|  | <column alignment="left" valignment="top" width="2.5cm"> | ||
|  | <column alignment="left" valignment="top" width="2.75cm"> | ||
|  | <column alignment="left" valignment="top" width="1.25cm"> | ||
|  | <column alignment="left" valignment="top" width="1.75cm"> | ||
|  | <column alignment="left" valignment="top" width="1.75cm"> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Name | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Residual | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Variables | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Measurement | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | ( | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | ) | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Measurement Uncertainty | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | PriorFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $z.\mathrm{localCoordinates}\left(x\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Ideal  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  / In  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | BetweenFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $z.\mathrm{localCoordinates}($ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\; x.\mathrm{between}\left(y\right))$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Ideal  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  / In  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | RangeFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x.\mathrm{range}\left(y\right)-z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="center" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Euclidean distance | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | BearingFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $z.\mathrm{localCoordinates}($ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $\; x.\mathrm{bearing}\left(y\right))$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="center" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Bearing of  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  position in frame  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | GenericProjection | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Factor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $K^{-1}\left(P\left(x^{-1}p\right)\right)-z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="center" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Perspective projection of  | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | <row> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \series bold | ||
|  | \size footnotesize | ||
|  | GeneralSFM | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Factor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $K^{-1}\left(P\left(x^{-1}p\right)\right)-z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $g$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Parameters | ||
|  | \begin_inset Newline newline | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | of  | ||
|  | \begin_inset Formula $K$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | Perspective projection of  | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | <cell alignment="left" valignment="top" topline="true" bottomline="true" usebox="none"> | ||
|  | \begin_inset Text | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | 
 | ||
|  | \size footnotesize | ||
|  | In  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | </cell> | ||
|  | </row> | ||
|  | </lyxtabular> | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \size default | ||
|  | 
 | ||
|  | \begin_inset Caption | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | Measurement functions and coordinate frames of factors provided with GTSAM. | ||
|  |  To simplify notation,  | ||
|  | \begin_inset Formula $K$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a camera calibration function converting pixels to normalized image | ||
|  |  coordinates, and  | ||
|  | \begin_inset Formula $P$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is the pinhole projection function. | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | All built-in GTSAM factors follow a consistent coordinate frame convention | ||
|  |  (though fundamentally how a measurement and its uncertainty are specified | ||
|  |  depends on the measurement model described by a factor). | ||
|  |  In all built-in GTSAM factors, the  | ||
|  | \emph on | ||
|  | noise model | ||
|  | \emph default | ||
|  | , i.e. | ||
|  |  the measurement uncertainty, should be specified in the coordinate frame | ||
|  |  of the measurement itself. | ||
|  |  This is part of a convention in GTSAM that tangent-space quantities (like | ||
|  |  Gaussian noise models and update delta vectors) are always in the coordinate | ||
|  |  frame of the element owning the tangent space. | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | PriorFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A PriorFactor is a simple unary prior. | ||
|  |  It encodes a direct measurement of the value of a variable  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , with the specified mean  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  and uncertainty, such that  | ||
|  | \begin_inset Formula $z.\mathrm{between}\left(x\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is distributed according to the specified noise model. | ||
|  |  From this definition and the definition of  | ||
|  | \series bold | ||
|  | between | ||
|  | \series default | ||
|  |  in Table | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset CommandInset ref | ||
|  | LatexCommand ref | ||
|  | reference "tab:Coordinate-frame-transformations" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , the measurement itself should be specified in the frame with respect to | ||
|  |  which  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is specified, while the uncertainty is specified in the coordinate frame | ||
|  |  of the measurement, or equivalently, in frame  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | BetweenFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A BetweenFactor is a measurement on the relative transformation between | ||
|  |  two variables. | ||
|  |  A BetweenFactor on variables  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  and  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  with measurement  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  implies that  | ||
|  | \begin_inset Formula $z.\mathrm{between}\left(x.\mathrm{between}\left(y\right)\right)$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is distributed according to the specified noise model. | ||
|  |  This definition, along with that of  | ||
|  | \series bold | ||
|  | between | ||
|  | \series default | ||
|  |  in Table | ||
|  | \begin_inset space ~ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \begin_inset CommandInset ref | ||
|  | LatexCommand ref | ||
|  | reference "tab:Coordinate-frame-transformations" | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , implies that the measurement is in frame  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , i.e. | ||
|  |  it measures  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  in  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , and that the uncertainty is in the frame of the measurement, or equivalently, | ||
|  |  in frame  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | RangeFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A RangeFactor measures the Euclidean distance either between two poses, | ||
|  |  a pose and a point, or two points. | ||
|  |  The range is a scalar, specified to be distributed according to the specified | ||
|  |  noise model. | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | BearingFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A BearingFactor measures the bearing (angle) of the  | ||
|  | \emph on | ||
|  | position | ||
|  | \emph default | ||
|  |  of a pose or point  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  as observed from a pose  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  |  The orientation of  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  affects the measurement prediction. | ||
|  |  Though, if  | ||
|  | \begin_inset Formula $y$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a pose, it's orientation does not matter. | ||
|  |  The noise model specifies the distribution of the bearing, in radians. | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | GenericProjectionFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A GenericProjectionFactor measures the pixel coordinates of a landmark  | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  projected into a camera  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  with the calibration function  | ||
|  | \begin_inset Formula $K$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  that converts pixels to normalized image coordinates. | ||
|  |  The measurement  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is specified in real pixel coordinates (thanks to the  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | uncalibration | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  function  | ||
|  | \begin_inset Formula $K^{-1}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  used in the residual). | ||
|  |  In a GenericProjectionFactor, the calibration is fixed. | ||
|  |  On the other hand, GeneralSFMFactor allows the calibration parameters to | ||
|  |  be optimized as variables. | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Subsection | ||
|  | GeneralSFMFactor | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | A GeneralSFMFactor is the same as a GenericProjectionFactor except that | ||
|  |  a GeneralSFMFactor also allows the parameters of the calibration function | ||
|  |   | ||
|  | \begin_inset Formula $K$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  to be optimized as variables, instead of having them fixed. | ||
|  |  A GeneralSFMFactor measures the pixel coordinates of a landmark  | ||
|  | \begin_inset Formula $p$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  projected into a camera  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  with the calibration function  | ||
|  | \begin_inset Formula $K$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  that converts pixels to normalized image coordinates. | ||
|  |  The measurement  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is specified in real pixel coordinates (thanks to the  | ||
|  | \begin_inset Quotes eld | ||
|  | \end_inset | ||
|  | 
 | ||
|  | uncalibration | ||
|  | \begin_inset Quotes erd | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  function  | ||
|  | \begin_inset Formula $K^{-1}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  used in the residual). | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Standard | ||
|  | \begin_inset Note Note | ||
|  | status collapsed | ||
|  | 
 | ||
|  | \begin_layout Section | ||
|  | Noise models of prior factors | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | The simplest way to describe noise models is by an example. | ||
|  |  Let's take a prior factor on a 3D pose  | ||
|  | \begin_inset Formula $x\in\SE 3$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | ,  | ||
|  | \family typewriter | ||
|  | Pose3 | ||
|  | \family default | ||
|  |  in GTSAM. | ||
|  |  Let  | ||
|  | \begin_inset Formula $z\in\SE 3$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  be the expected pose, i.e. | ||
|  |  the zero-error solution for the prior factor. | ||
|  |  The  | ||
|  | \emph on | ||
|  | unwhitened error | ||
|  | \emph default | ||
|  |  (the error vector not accounting for the noise model) is | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | h\left(x\right)=\log\left(z^{-1}x\right)\text{,} | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | where  | ||
|  | \begin_inset Formula $\cdot^{-1}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is the Lie group inverse and  | ||
|  | \begin_inset Formula $\log\cdot$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is the logarithm map on  | ||
|  | \begin_inset Formula $\SE 3$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  |  The full factor error, including the noise model, is | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | e\left(x\right)=\norm{h\left(x\right)}_{\Sigma}^{2}=h\left(x\right)^{\t}\Sigma^{-1}h\left(x\right)\text{.} | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | [ Skipping details of the derivation for now, for lack of time to get a | ||
|  |  useful answer out quickly ] | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | The density induced by a noise model on the prior factor is Gaussian in | ||
|  |  the tangent space about the linearization point. | ||
|  |  Suppose that the pose is linearized at  | ||
|  | \begin_inset Formula $\lin x\in\SE 3$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , which we assume is near to  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  |  Let  | ||
|  | \begin_inset Formula $\delta x\in\R 6$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  be an update vector in local coordinates (a twist). | ||
|  |  Then, the factor error in terms of the update vector  | ||
|  | \begin_inset Formula $\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | e\left(\delta x\right)=\norm{h\left(\lin x\exp\delta x\right)}_{\Sigma}^{2} | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | We can see why the covariance  | ||
|  | \begin_inset Formula $\Sigma$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is in the body frame of  | ||
|  | \begin_inset Formula $x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  by looking at the linearized error function, | ||
|  | \begin_inset Formula  | ||
|  | \begin{align*} | ||
|  | e\left(\delta x\right) & \approx\norm{\log\left(z^{-1}\lin x\exp\delta x\right)}_{\Sigma}^{2}\\ | ||
|  |  & \approx\norm{\log\left(z^{-1}\lin x\right)+\delta x}_{\Sigma}^{2} | ||
|  | \end{align*} | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | Here we see that the update  | ||
|  | \begin_inset Formula $\exp\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  from the linear step  | ||
|  | \begin_inset Formula $\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is applied in the body frame of  | ||
|  | \begin_inset Formula $\lin x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , because of the ordering  | ||
|  | \begin_inset Formula $\lin x\exp\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  |  Furthermore,  | ||
|  | \begin_inset Formula $z^{-1}\lin x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is a constant term, so we can also see that the covariance  | ||
|  | \begin_inset Formula $\Sigma$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is actually applied to the linear update vector  | ||
|  | \begin_inset Formula $\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | This means that to draw random pose samples, we actually draw random samples | ||
|  |  of  | ||
|  | \begin_inset Formula $\delta x$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  with zero mean and covariance  | ||
|  | \begin_inset Formula $\Sigma$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , i.e. | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | \delta x\sim\mathcal{N}\left(0,\:\Sigma\right)\text{.} | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Section | ||
|  | Noise models of between factors | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \begin_layout Plain Layout | ||
|  | The noise model of a BetweenFactor is a bit more complicated. | ||
|  |  The unwhitened error is | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | h\left(x_{1},x_{2}\right)=\log\left(z^{-1}x_{1}^{-1}x_{2}\right)\text{,} | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | where  | ||
|  | \begin_inset Formula $z$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  is the expected relative pose between  | ||
|  | \begin_inset Formula $x_{1}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  and  | ||
|  | \begin_inset Formula $x_{2}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , i.e. | ||
|  |  the factor has zero error when  | ||
|  | \begin_inset Formula $x_{1}z=x_{2}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | . | ||
|  |  If we consider the density on the second pose  | ||
|  | \begin_inset Formula $x_{2}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  induced by holding the first pose  | ||
|  | \begin_inset Formula $x_{1}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  |  fixed, we can see that the covariance is applied to the linear update in | ||
|  |  the body frame of the second pose  | ||
|  | \begin_inset Formula $x_{2}$ | ||
|  | \end_inset | ||
|  | 
 | ||
|  | , | ||
|  | \begin_inset Formula  | ||
|  | \[ | ||
|  | e\left(\delta x_{2}\right)\approx\norm{\log\left(z^{-1}x_{1}^{-1}x_{2}\exp\delta x_{2}\right)}_{\Sigma}^{2}. | ||
|  | \] | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | If we hold the second pose fixed, the covariance is applied as follows (actually | ||
|  | , what frame is it in now??) | ||
|  | \begin_inset Formula  | ||
|  | \begin{align*} | ||
|  | e\left(\delta x_{1}\right) & \approx\norm{\log\left(z^{-1}\left(x_{1}\exp\delta x_{1}\right)^{-1}x_{2}\right)}_{\Sigma}^{2}\\ | ||
|  |  & =\norm{\log\left(z^{-1}\exp-\delta x_{1}x_{1}^{-1}x_{2}\right)}_{\Sigma}^{2} | ||
|  | \end{align*} | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_inset | ||
|  | 
 | ||
|  | 
 | ||
|  | \end_layout | ||
|  | 
 | ||
|  | \end_body | ||
|  | \end_document |