[Gdal-dev] Looking for some guidance...

[Sandy Pyke]

Hello all,

I am working on a project where I have multiple large raster maps as my
data source. The output of the project is to be a map scaled to a
certain size covering a certain area. The output map may need data from
1 to 4 of the larger maps to generate the output map.

So far I have worked around converting my raster maps to GeoTIFF with
the proper georeferencing applied, loading bounding boxes for these maps
as well as the file names into a PostGIS database, calculating the
desired map coverage, and extracting the relevant file names of the
required output maps from the PostGIS database. I now know which files I
need for my source data, I need to create the output map.

These output maps will be 1280 x 1024 x 8 maps and use a GCS of WGS84.

I have been able to get this to work on the command line using the
following commands:

gdalwarptest -te -73.61837 45.38504 -73.32745 45.54867 \
             -tr 1280 1024 inputfile1.tif outputfile.tif

gdalwarptest -srcnodata 0 inputfile2.tif outputfile.tif
gdalwarptest -srcnodata 0 inputfile3.tif outputfile.tif
gdalwarptest -srcnodata 0 inputfile4.tif outputfile.tif

gdal_translate outputfile.tif compressedoutput.png

I essentially want to get the same result, but in C / C++ code.

Conceptually I want to do the following:

- Generate the output dataset in memory
- Warp the source image(s) to the memory dataset
- Translate the memory dataset to a compressed image file

The API tutorials do make mention of the ability to create "in-memory"
datasets but no information is given on how to do this. Can anyone offer
some insight on this? Specifically, what driver should I use?

Also, if anyone can offer some insight on how I would go about
implementing my desired functionality I would appreciate it.

Thank you.

Sandy Pyke

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