[gdal-dev] Extract elevation from (latitude, longitude)

[Chaitanya kumar CH]

Carmelo,

In the code n30.dt0 is some raster image file. Replace it with your image
path.
The array named 'data' was renamed to pippo. Correct that.

Refer to GDALDataset::GetGeoTransform() method at
http://www.gdal.org/classGDALDataset.html

Use GDALDataset::RasterIO() or GDALRasterIO while treating the pointer to a
double variable as the buffer (pData in the function definition).

On Tue, Aug 31, 2010 at 8:41 PM, Carmelo Terrasi
<terrasi.carmelo at gmail.com>wrote:

> Hello everybody,
> first of all my apologies cause I'm a newbie with this stuff...
>
> I'm trying to build a function able to extract altitude from latitude and
> longitude as parameters.
> Something like that: *double MyElevation(double lat, double lon)*
> *
> *
> I'm using Dted level 0 to get the elevation (I've already read this post:
> http://www.osgeo.org/pipermail/gdal-dev/2010-February/023457.html )
> But I got lost... :(
>
> *GDALAllRegister();
> *
> *pointerToDataSet=(GDALDataset*) GDALOpen("n30.dt0", GA_ReadOnly);*
> * *
> *double data[6];*
> *double longitude, latitude;*
> *
> *
> *pointerToDataSet->GetGeoTransform(data);*
> *
> *
> *longitude=???;*
> *latitude=???;*
> * *
> *double x = (longitude - pippo[0]) / pippo[1];*
> *double y = (latitude - pippo[3]) / pippo[5];*
> * *
> *GDALRasterBand* pointerToBand;*
> * *
> *pointerToBand=pointerToDataSet->GetRasterBand(1);*
> * *
> *float *elevation;*
> * *
> *pointerToDataSet->RasterIO(?,?, ... , ?);*
> *pointerToBand->RasterIO(?,?, ... , ?);*
>
>
> I supposed I had to store elevation data into the buffer I created, I mean
> the float pointer.
> I got confused among these:
> - the file *.dt0
> - longitude and latitude
> - parameters for RasterIO()
>
> Every tips will be very appreciated, thanks a lot for your patience,
> Regards,
> Carmelo
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
Best regards,
Chaitanya kumar CH.
/tʃaɪθənjə/ /kʊmɑr/
+91-9494447584
17.2416N 80.1426E
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20100831/e88750cd/attachment.html