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Many equations from the SICD and SIDD documentation are included in SIX (note that in the descriptions below, following document convention, scene and ground are used interchangeably, as are image and slant):

Description	Document Reference	SIX Implementation	Additional Notes
Precise scene to image grid projection (iterative)	SICD Volume 1, Section 6.1	ProjectionModel:: sceneToImage()	Overloadings exist to optionally use sensor model adjustable parameters.
Precise image to scene grid projection via a ground plane reference point and ground plane normal.	N/A	ProjectionModel:: imageToScene()	Overloadings exist to optionally use sensor model adjustable parameters.
Precise image to scene grid projection to a constant height surface and surface normal	SICD Volume 3 Section 9.1 (draft)	ProjectionModel:: imageToScene()	Overloadings exist to optionally use sensor model adjustable parameters.
Compute the R/Rdot contour from an image grid point	SICD Volume 3 Section 4	ProjectionModel:: computeContour()	Subclassed for each IFP algorithm and grid type.
R/Rdot contour ground plane intersection	SICD Volume 3 Section 5.2	ProjectionModel:: contourToGroundPlane()
Row/col <--> ECEF conversions	SIDD Volume 1 Section 3	GridECEFTransform:: rowColToECEF() and GridECEFTransform:: ecefToRowCol()	Subclassed for each grid (PGD, GGD, CGD); CGD support is limited.

In addition, the scene::ProjectionPolynomialFitter class can be used to sample a grid of points using the precise ProjectionModel::sceneToImage() methods and then fit a polynomial to it to use to apply to an entire image (frequently it's too expensive to precisely project each point in a large image). This class is highly configurable in terms of the number of points in the grid to use, the order of the polynomial to fit, the units (pixels vs. meters) to provide the polynomial in, and which direction (image --> scene vs. scene --> image) to provide. A time COA polynomial can be fit at the same time for convenience.

The scene module also contains a variety of coordinate transforms (ECEF, lat/lon/alt, ENU, NED) and a WGS-84 ellipsoid model which may be useful.