[vtkusers] How to import NASA SRTM DEM data into VTK

[Elvis Dowson]

Hi,
          Looking at the list of VTK classes, I think that  
vtkImageReader2  could be used to read the SRTM DEM data file, with  
byte swapping on. A vtkImageData object is obtained from  
vtkImageAlgorithm::GetOutput(), which is a superclass of  
vtkImageReader2.

One thing I am not so sure of is what I should do about the following  
vtkImageReader2  methods
SetDataExtent (int, int, int, int, int, int)
SetDataSpacing (double, double, double)
SetDataOrigin (double, double, double)

If the value in SRTM array data position [0][0] = +100, then do I  
store this at the following coordinate location x=0, y=0, z=+100 ? Is  
this correct? That is, the first element is stored at the lower left  
cornet and the z value is interpreted as a scalar value for the height  
field? Is this how it works when reading DEM files, and what  
vtkDEMReader does?

Best regards,

Elvis Dowson


>
> In essence, SRTM data is nothing but raster data, stored using 16- 
> bit signed integer. Depending upon the arc length, you will have  
> either 1201x1201 or 3601x3601 data elements. So, all I have to do is  
> to import each value, taking take to perform byte swapping, since I  
> am using a Mac Book Pro with an Intel processor, and read in two  
> bytes of data, corresponding to a pixel element value, that can  
> later be used to create a raster image of height field data.
>
>
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