[Gdal-dev] mosaic by vrt

[Fu Chen]

Hi!
I didn't know whether you read the last email I sent. Maybe something wrong in the language coding. I can't read it in the archive of GDAL.
I try to mosaic tens of images into a vrt. First turn them into same project for example lcc. This is okay by the help of Frank.
But I find it difficult to write the vrt because the distance between images are not the integer times of pixel size (tr x y in gdalwarp parameter). And in vrt, the Xoff Yoff should be integer. So I have to round the distance to integer times of pixel size. It's not precise, I think.
Is there a way that make upperleft point of each image generated from gdalwarp be the integer times of pixel size? That will make all Xoff, Yoff in vrt be really integer.
In fact, I have tried to use -te to set the georeferenced extents. But i have to gdalinfo from the first generated tiff and set the -te manually to get what i want. So the process include gdalwarp twice and some manualcalculation (although it can program by a script). 
I think the best way is add a switch in galwarp command line parameter, make it generate right image what I want in once.
BTW, is it possible to make vrt accept the double as xoff and yoff? That will images in same project mosaic without other additional work.
Any suggestion?

Best regards

Fu CHEN