Create Raw RPC Coefficient Metadata

To simulate raw RPC metadata, create a simple test file and write some RPC metadata to the file. For this test file, create a toy image and a referencing object associated with the image.

myimage = zeros(180,360);

latlim = [-90 90];

lonlim = [-180 180];

R = georefcells(latlim,lonlim,size(myimage));

Create an RPCCoefficientTag metadata object and set some of the fields. The toolbox uses the RPCCoefficientTag object to represent RPC metadata in human readable form.

rpctag = map.geotiff.RPCCoefficientTag;

rpctag.LineOffset = 1;

rpctag.SampleOffset = 1;

rpctag.LineScale = 2;

rpctag.SampleScale = 2;

rpctag.GeodeticHeightScale = 500;

Write the image, the associated referencing object, and the RPCCoefficientTag object to a file.

geotiffwrite('myfile',myimage,R,'RPCCoefficientTag',rpctag)

Read Raw RPC Coefficient Metadata

Read the RPC coefficient metadata from the test file using the imfinfo function. When it encounters unfamiliar metadata, imfinfo returns the data, unprocessed, in the UnknownTags field. Note that the UnknownTags field contains an array of 92 doubles. This is the raw RPC coefficient metadata, read from the file in unprocessed form.

info = imfinfo('myfile.tif');

info.UnknownTags

ans = struct with fields:

ID: 50844

Offset: 10676

Value: [1x92 double]

Write Raw RPC Metadata to a File

Write the raw RPC metadata to a file. First, extract the RPC coefficient metadata from the info structure.

value = info.UnknownTags.Value;

Then, construct an RPCCoefficientTag object, passing the raw RPC metadata (array of 92 doubles) as an argument.

rpcdata = map.geotiff.RPCCoefficientTag(value)

rpcdata =

RPCCoefficientTag with properties:

BiasErrorInMeters: -1

RandomErrorInMeters: -1

LineOffset: 1

SampleOffset: 1

GeodeticLatitudeOffset: 0

GeodeticLongitudeOffset: 0

GeodeticHeightOffset: 0

LineScale: 2

SampleScale: 2

GeodeticLatitudeScale: 1

GeodeticLongitudeScale: 1

GeodeticHeightScale: 500

LineNumeratorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

LineDenominatorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

SampleNumeratorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

SampleDenominatorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

Pass the RPCCoefficientTag object to the geotiffwrite function and write the RPC metadata to a file.

geotiffwrite('myfile2',myimage,R,'RPCCoefficientTag',rpcdata)

To verify that the data was written to the file, read the RPC metadata from the TIFF file using geotiffinfo. Compare the returned RPC metadata with the metadata written to the test file.

ginfo = geotiffinfo('myfile2');

ginfo.GeoTIFFTags.RPCCoefficientTag

ans =

RPCCoefficientTag with properties:

BiasErrorInMeters: -1

RandomErrorInMeters: -1

LineOffset: 1

SampleOffset: 1

GeodeticLatitudeOffset: 0

GeodeticLongitudeOffset: 0

GeodeticHeightOffset: 0

LineScale: 2

SampleScale: 2

GeodeticLatitudeScale: 1

GeodeticLongitudeScale: 1

GeodeticHeightScale: 500

LineNumeratorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

LineDenominatorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

SampleNumeratorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

SampleDenominatorCoefficients: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]