Frequently Asked Questions

Installation

ImportError: libvl.so

CARS is correctly installed but I get the following error at runtime:

ImportError: libvl.so: cannot open shared object file: No such file or directory

libvl.so is a dynamic library from VLFeat (see the section Install) and it must be placed somewhere in the filesystem.

The GNU standards recommend installing (or copying) by default all libraries in /usr/local/lib (see https://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html).

If your don’t have sudo rights, you should add the parent directory of this library to LD_LIBRARY_PATH and export it.

Input data

How to create CARS compatible ROI input data with OTB ?

Please, see the section Make input ROI images to generate the ROI input images.

Did you find this error :”The image and the color haven’t the same sizes”?

If do you use Pleaides sensor images, the color image can’t be superimposable on the CARS input image.

Please, see the section Make a simple pan sharpening to make a simple pan sharpening with OTB.

How to generate input images in epipolar geometry from grids ?

To generate the images in epipolar geometry from the grids computed by cars and the original images, one can refer to the Orfeo Toolbox documentation here .

How to make a water mask with gdal on RGBN images?

Please, see the section Make a water mask to make a water mask with OTB.

Output data

How to generate output files overview ?

Considering bulky files, it can be recommended to generate an overview file with GDAL before opening it with QGIS:

$ gdaladdo -ro -r average dsm.tif 2 4 8 16 32 64