Ampcor to support URL as file input

[whyjz]

Hi,

I have been using ISCE, particularly the Ampcor component, for my feature tracking package CARST. I run feature tracking using both optical and SAR images.

My question is: when the input file is stored on a remote server and is accessed via a URL, e.g., a GeoTIFF file on the Amazon web service, the iscesys.ImageApi.DataAccessor cannot open it because it needs a VRT file that is stored on the same path as the input file, and we usually don't have the write permission on a remote server (i.e. not able to create the necessary VRT file on the same path).

One workaround is to make it more flexible for generating/selecting the VRT file path (for example, by changing line 145 of components/iscesys/ImageApi/DataAccessor/DataAccessorPy.py) I just made some modification for that and made sure it's working. I wonder if that's okay for me to make a PR, or if you have a better idea to deal with this issue. Thanks!

[piyushrpt]

You should be able to create a local VRT file with source pointing to remote resource and corresponding xml file, and ISCE should be able to work with it - for reading data directly. Yes, please issue a PR - would be good to know if any other changes were needed.