Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

Having used QGIS for quite some time for mapping, I was 'forced' to dig into GRASS as pansharpening is not directly executable in QGIS. After understanding more or less the structure, I did some trials with i.fusion.brovey. I was able to generate the rasters with 15m resolution, but when loading into QGIS I can not achieve/recuperate the nice colour contrast as is present in the original 30m rasters.

In an earlier post someone confirmed that and proposed to use another function for landsat: 'i.his.rgb' (after using i.landsat.toar, which I don't use). He starts to convert min/max to 1-255 before using i.his.rgb...My original rasters have a range of 0-65535. It did not work out for me...

I quit after some days of struggling to just perform a pansharp, I feel stuck... Why should just applying i.pansharp not work for Landsat as suggested by others? Can someone suggest a more straightforward workflow to execute pansharpening of Landsat 8 images? Looking forward to some advice, thanks in advance...

share|improve this question
add comment

3 Answers 3

up vote 1 down vote accepted

Thanks Michal and Markus. Finally I was able to do the pansharpening with the indicated function brov. Once performed in GRASS, I exported the RGB rasters to gdal GTiff with as data type Uint16. Markus, I have been downloading and using several Landsat 8 images (tiff of each of the 11 bands), obtaining nice visual results, both in natural/false color. To my knowledge, the original landsat tiffs come as Uint16 with values ranging from 0 to 65535 (or am I missing something?)...Thanks for the GRASS LANDSAT link...

share|improve this answer
    
Please upvote helpful answers and accept answers that solve your problem. –  underdark Jun 29 '13 at 18:46
2  
Yes, Landsat 8 images are stored as Uint16 types. –  webrian Aug 9 '13 at 14:21
add comment

Take a look at i.landsat.rgb - Performs auto-balancing of colors for LANDSAT images, probably before running the pansharpening. You may also consider to convert the digital numbers of the individual channels to top-of-atmosphere radiance or reflectance with i.landsat.toar. See also http://grasswiki.osgeo.org/wiki/LANDSAT

BTW: having a range of 0-65535 for original LANDSAT data is odd since they are delivered as 8 bit channels (0-255). So check your input data first.

Update: 10/2013

For a simplified procedure with current GRASS GIS 7, see the page enter image description hereProcessing Landsat 8 data in GRASS GIS 7: RGB composites and pan sharpening

share|improve this answer
add comment

You can also try Monteverdi to perform pansharpening. This tool can consume regular GeoTIFFs as input (however, separate multispectral bands have to be merged into one multiband raster), and performs reasonably well.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.