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Map The Location of Pixels with Max DN Value in a DEM or other raster

by Technical Evangelist ‎03-29-2018 12:27 PM - edited ‎03-29-2018 12:44 PM (675 Views)

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Description:

 

Image statistics will tell you what the maximum data value is in a raster layer (such as the highest value in a DEM), but sometimes you need to know where that value exists spatially in the dataset. For example, when evaluating the quality of a terrain surface you want to drive to the locations of high values and visually inspect to determine if it represents an erroneous spike in the data. But determining where specific DN values exist isn't as easy as it sounds in a raster dataset.

 

 Green label dot indicates location of highest DEM value (6072m)
 map_max_result.png

 

This model finds and maps the MAXimum pixel value locations of any raster. It was originally designed for locating the MAX of a DEM, but it can handle multiple band datasets as well (by calculating a Stack Max). It will output a point shapefile which describes the locations that have the maximum pixel value. In the case of Unsigned data (and flatter areas) it might return multiple points, whereas in case of higher relief the output will most likely be just one point.

 

The Distance parameter allows the user to define a range of values, which obviously leads to multiple points. The Distance parameter is particularly useful in the case of floating point DEMs where you might want to identify pixels with value 1993.35 and 1993.36m as being "highest points" 

 

The output points are attributed with the height (DN) value at that location.

 

map_max_pixel_locations_v16_5_2.gmdx
map_max_model.PNG

 

 

Input parameters:

 

Raster DEM: Name of the input raster file to be analysed for  the locations of Maximum DN value(s)

Distance allowed from Max: Tolerance, generally used for Floating Point DEMs, to define the range of values to be considered "maximum". For example, if the Maximum height value were 1445m (in an Integer dataset) and a Distance of 0 were specified, only pixels with a value of 1445 would be mapped. Whereas if a Distance of 2 were specified, pixels with values 1443, 1444 and 1445 would be mapped.

Output Shape: Output shapefile name. Each point reflects the location of a pixel with the maximum DN value (plus or minus the Distance tolerance).

 

map_max_run.png

 

   

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