Timeline for How to calculate an hypsographic curve of a raster trhough a DEM
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Sep 13, 2012 at 20:11 | comment | added | umbe1987 | Incredibly, I tried to search all the 169 pixels specified in the MODIS Attribute Table, and couldn't find them, so I used an if statement to create a mask of those pixels and the output says there are 6 pixels of 100 value! Have no clue what happened. Moreover, all the classes are strange in the MODIS AttTab, but when I attempt the same if statement they match with the output data summing of the zonal histogram table. I've been processing lot of MODIS and now I'm thinking their Attribute Tables are not good as they are without recalculating all the variables in them with the RasterCalculator. | |
| Sep 13, 2012 at 19:48 | comment | added | umbe1987 | I succeded resampling it and now pixels look fine (they do overlap!). Nevertheless, my resuslts with the zonal histograms are still the same!!!! The most in disagree is the class 100 ("lake ice"). When I sum up all the values within this class in the Table calculated with the zonal histogram I should get more or less the same value as the MODIS table, but it gives me a 6 while the original one is 169! No clue why... | |
| Sep 13, 2012 at 19:09 | comment | added | dmahr | @user9518 Use the Resample tool in Spatial Analyst to manually resample. Don't forget to set the Snap Raster environment in the new geoprocessing window. | |
| Sep 13, 2012 at 18:38 | comment | added | umbe1987 | I think I found the reason why the two rasters are not perfectly overlapping each other: I started my work by clipping the MODIS with the DEM and only later I resampled the pixel size of the DEM to match that of the MODIS. So I think when I first performed the clip, the tool has clipped the MODIS by "cuttting each pixels somewhere inside it", and so now I'm having problems. Question: whuber, how can I manually resample it? Can I convert it to graphic, move its position and then convert it back to a raster? It would be a lot of work if I had to re-do everything, even if I can use Python... | |
| Sep 13, 2012 at 18:27 | comment | added | umbe1987 | I tried to set both the snap ant the extent from the Environment setting, but I still get the same result... | |
| Sep 13, 2012 at 16:58 | comment | added | whuber | +1 It may be useful to know that Zonal Histogram does not count incorrectly. First--behind the scenes--ArcGIS automatically resamples one (or both) of the rasters to a common grid. Then it does its work. So the key to getting verifiable, reproducible results is to prevent ArcGIS from changing your data. Do this by manually resampling all rasters before performing any analysis. | |
| Sep 13, 2012 at 5:37 | comment | added | Tomek | Also try to set your Extent (resources.arcgis.com/en/help/main/10.1/index.html#/…) in environmental settings. | |
| Sep 13, 2012 at 2:59 | history | answered | dmahr | CC BY-SA 3.0 |