16.1. add_spot_rpc

The add_spot_rpc tool creates an RPC model to approximate a SPOT5 sensor model. The RPC model can be appended to the end of a SPOT5 metadata file, allowing it to be used with the RPC session type in other ASP tools. The most important application is to map project SPOT5 images, then to perform stereo on the map projected images with the spot5maprpc session type.

If the output file does not exist, a new file is created containing the RPC model. Otherwise the RPC model is appended to an existing file. When an existing SPOT5 metadata file is the output file, the new RPC model is properly inserted into the file so that it is ready to use.

An example for how to use this tool is given in Section 8.22.

Usage:

add_spot_rpc <input metadata file> -o <output file>

It is important to note that the tool expects the minimum and maximum simulation box heights (in meters, above the datum) in which to compute the RPC approximation. The defaults are 0 and 8000, corresponding to sea level and the highest location on Earth. Narrowing down these numbers (if it is known what range of terrain heights is expected) may result in slightly more accurate models.

Command-line options for add_spot_rpc:

-o, --output-prefix <arg>

Specify the output prefix.

--min-height <arg (default: 0)>

The minimum height (in meters) above the WGS84 datum of the simulation box in which to compute the RPC approximation.

--max-height <arg (default: 8000)>

The maximum height (in meters) above the WGS84 datum of the simulation box in which to compute the RPC approximation.

--num-samples <arg (default: 100)>

How many samples to use between the minimum and maximum heights.

--penalty-weight <arg (default: 0.1)>

Penalty weight to use to keep the higher-order RPC coefficients small. Higher penalty weight results in smaller such coefficients.

-v, --version

Display the version of software.

-h, --help

Display this help message.