Cassanova, Bill wrote:
Thank you for your help.
Couple more questions:
(1)
After the call to GDALGenImgProjTransform( ..., ..., ..., double *x,
double *y, ..., ... );
I am assuming that the x and y arguments contain the new lat-lon values
from the new projection and does not contain the data from the grid. In
other words I would need to maintain the data in a matrix of my own and
then given the results of X and Y determine an appropriate offset into
the rows and columns of that matrix. That being said, I would assume
that when data is re-projected that the raster now has a new set of
corner points but the same number of rows and columns of data as was
original. Am I correct? Do I have anyway of determining the new corner
points? Has the original number of rows and columns changed?
Bill,
The function does not warp the raster. It is just a transformer to make
it easy to get from some georeferenced image space back to a particular
pixel/line location. So you would feed in long/lat coordinates in
x/y and after the trasnform function returns these variables will
hold pixel/line locations. You could then use GDAL's RasterIO() to
read the actual pixel values at that location - or you could have read
the whole image into RAM and pull it from an array in memory.
(2) My assumption is the C API GDALCreateGenImgProjTransformer and
GDALGenImgProjTransform function calls do not have C++ equivalents
buried in one of the classes somewhere. I looked briefly at gdalwarper
and saw a few methods that looked similar but nothing that matches the
functionality of these calls.
That is correct, just use the C entry points.
--
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I set the clouds in motion - turn up | Frank Warmerdam, [email protected]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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