weixj, You can get some free samples at http://www.webgis.com/terr_us1deg.html
On Wed, May 2, 2012 at 1:45 PM, weixj <[email protected]> wrote: > Thank you for your answer. > I want to know that where I can get the free DEM data? > I want a sample data,and test my program. > > Thank you. > > > > At 2012-05-02 12:57:41,"Chaitanya kumar CH" <[email protected]> > wrote: > > weixj, > > Digital Elevation Model is a type of data. In this context, it is a grid > of elevation values stored in a raster file. > DEM refers to height. The underlying raster format can be anything. > > The only reference I found for .gmp format is "Global Mapper Package". > Perhaps you can find more on the global mapper forums and by opening it in > a binary editor. > > If the data is stored as raw data, you may be able to read it after > creating a .vrt file to describe it. > > On Wed, May 2, 2012 at 8:03 AM, weixj <[email protected]> wrote: > >> DEM is a data format,and the file name extension has many formats,is it >> right? >> My colleage give me file and its name is 90mDataHeight.gmp,and I use the >> following code read it,and find that it can not open the file. >> >> code: >> GDALAllRegister(); >> poDataset=(GDALDataset >> *)GDALOpen(fileName.toLatin1().data(),GA_ReadOnly); >> if(poDataset==NULL) >> { >> QMessageBox::warning(0,"","can not open file:"+fileName); >> return false; >> } >> >> I do not know why? >> How many formats of DEM file? >> >> Thank you. >> >> 在 2012-04-25 20:11:45，"Chaitanya kumar CH" <[email protected]> 写道： >> >> sure >> >> >> 2012/4/25 weixj <[email protected]> >> >>> If the file is DEM?the same? >>> >>> >>> At 2012-04-24 19:36:11,"Chaitanya kumar CH" <[email protected]> >>> wrote: >>> >>> weixj, >>> >>> You can use the -projwin option of gdal_translate utility. >>> >>> http://www.gdal.org/gdal_translate.html >>> >>> 2012/4/24 weixj <[email protected]> >>> >>>> I have a tiff file and four points' coordination(and they are in the >>>> range of the min and max value of the coordination of the tiff file,I want >>>> to generate a new tiff file,and the edge of it is constructed by the four >>>> points. >>>> >>>> Thank you in advance. >>>> >>>> >>>> ------------------------------ >>>> 网易Lofter，专注兴趣，分享创作！ <http://www.lofter.com/> >>>> _______________________________________________ >>>> gdal-dev mailing list >>>> [email protected] >>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev >>>> >>> >>> >>> >>> -- >>> Best regards, >>> Chaitanya kumar CH. >>> >>> +91-9494447584 >>> 17.2416N 80.1426E >>> >>> >>> >>> ------------------------------ >>> 网易Lofter，专注兴趣，分享创作！ <http://www.lofter.com/> >> >> >> >> >> -- >> Best regards, >> Chaitanya kumar CH. >> >> +91-9494447584 >> 17.2416N 80.1426E >> >> >> >> ------------------------------ >> 网易Lofter，专注兴趣，分享创作！ <http://www.lofter.com/> > > > > > -- > Best regards, > Chaitanya kumar CH. > > +91-9494447584 > 17.2416N 80.1426E > > > > -- Best regards, Chaitanya kumar CH. +91-9494447584 17.2416N 80.1426E
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