USGS MIPS Geom Documentation

USGS MIPS Geom Documentation

This program applies a geometric transformation to an image defined by a transformation file(TFILE) generated by any of several different programs or procedures. The transformation may be designed to correct for geometric distortions in the original image or to purposely warp an image. In the process of transforming pixels from one location in the image to another, the user can select a nearest neighbor or cubic convolution resampling option.

GEOM is basically the 'workhorse' that applies a given geometric transformation to an image. To generate the desired transformation file/instructions the user must first use programs like TFGEN, TFWGEN, TFCOMP or SCALE. For image-to-map and image-to-image type transformations TFGEN or TFWGEN are required(i.e., GEOM just moves pixels around, while TFGEN and TFWGEN tell it how and where to move them to).

Files

This program requires two input files. The FIRST input file must be the image to be transformed and can be an unsigned 8-bit , signed 16-bit or 32-bit floating point image file; it generates an output image of the same bit type. The SECOND input file is the transformation file that was created by a previous program (e.g. TFGEN, TFROTSCL, TFCOMP, etc --- it tells GEOM how to transform/project the image). A third input file is an optional work file that can be specified by the user(generally this is not required and a default name is used by the program).

Parameters

NN or CC: These parameters are used to select the resampling method to be used in creating the output image file. Selecting NN causes the output image to have a nearest neighbor resampling while CC will apply a cubic convolution resampling. The default is NN.
MINIMIZE: This parameter tells Geom to create an output image file as small as possible without loosing valid pixels. With the parameter set, GEOM will find the minimum latitude/longitude boundary in which the transformed/projected image will fit and use those as the image boundary. With out it set, GEOM uses the latitude/longitude boundary specified by the user or transformation file as the boundary(this can be much larger than needed if not carefully selected). The default is to not set this option.

Examples

Landsat MSS Band 6 before GEOM.

[Example Image]

Landsat MSS Band 6 with 45 degree rotation. This image is the result of running TFROTSCL to generate a transformation file to rotate the image 45 degrees and then using the transformation file as input to the program GEOM.