Crash with gdalwarp -multi with RPC_DEM

[Even Rouault]

Reported as ​https://lists.osgeo.org/pipermail/gdal-dev/2017-April/046489.html

"""

I've run into issues using gdalwarp for an RPC ortho. My input GeoTiff file contains the required information in the RPC metadata domain, and the command runs fine under the GDAL 2.1.0 command line utility (windows 7, 64-bit):

gdalwarp -multi -tap -et 0.0 -r cubic -srcnodata 0 -rpc -overwrite -to "RPC_DEM_INTERPOLATION=CUBIC" -to "RPC_DEM_MISSING_VALUE=0" -to "RPC_DEM=D:\Temp\bug_gdalwarp\DEM.tif" -tr 30 30 -t_srs "+proj=aea +lat_1=44.75 +lat_2=55.75 +lat_0=40 +lon_0=-96 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs" D:\Temp\bug_gdalwarp\IMG.tif D:\Temp\bug_gdalwarp\IMG_ortho.tif

However, the same command and inputs fail under GDAL 2.1.3, without error messages, after getting to about 20% on the progress bar. It simply pops up the usual window saying "gdalwarp.exe has stopped working. A problem caused the program to stop working correctly"...

Strangely, it only crashes for some images, while some are OK. I haven't been able to pinpoint the cause. """

[Even Rouault]

In 38092:

gdalwarp: fix crash when -multi and -to RPC_DEM are used together (fixes #6869)

[Even Rouault]

In 38093:

gdalwarp: fix crash when -multi and -to RPC_DEM are used together (fixes #6869)

[Even Rouault]

In 38094:

gdalwarp: fix crash when -multi and -to RPC_DEM are used together (fixes #6869)