[FWTools] Converting a HGT file to a 16bit .png fills image with black.

[Jon Jones]

It is pure black.

I am using hgt data from ftp://e0srp01u.ecs.nasa.gov/ so that should be
16bit I believe. One thing I did try is convert the data to a 16 bit geotiff
file and then convert that to a 16 bit png but I get the same results.

Thanks,
Jon Jones

On Tue, Jan 27, 2009 at 2:01 PM, Matt Wilkie <matt.wilkie at gov.yk.ca> wrote:

> > If I use "gdal_translate -ot Int16 -of PNG infile.hgt outfile.png" I get
> > an 8 bit grayscale image. If I use "gdal_translate -ot UInt16 -of PNG
> > infile.hgt outfile.png " I get a 16 bit grayscale image but now it is
> > pure black. Any ideas?
>
> With the latter case is it pure black or just really dark? Bring the image
> into a photo program (gimp, photoshop) and use Auto-levels (don't save
> though or it will alter the values).
>
> For the former, I don't have any problem creating int16 .png from a geotiff
> elevation file. Perhaps that's because the source is int16 though.
>
> cheers,
>
>
> matt wilkie
> --------------------------------------------
> Geographic Information,
> Information Management and Technology,
> Yukon Department of Environment
> 10 Burns Road * Whitehorse, Yukon * Y1A 4Y9
> 867-667-8133 Tel * 867-393-7003 Fax
> http://environmentyukon.gov.yk.ca/geomatics/
> --------------------------------------------
>
>
> Jon Jones wrote:
>
>>
>> --
>> Jon Jones
>>
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