I tried to use two methods to calculate the volume of basin in New Mexico.
First, in the attached file (RasterImage.jpg), I created the interpolated raster surface of top apart of the unit rock from points by the attribute "elevation". Then in the "Layer Properties", I clicked the "Classify" and then used the number "Sum" in "Classification Statistics" to multiply the unit pixel area (100*100 square ft). The bottom part of the unit rock was calculated in the same way. Then the difference between top and bottom part of raster volumes would represent the volume of the unit rock.
Second, in the attached file(VolumeCalculation.xlsx), I have a question about the tool �??Surface Volume�?� in 3D Analyst. I want to calculate the volume between two interpolated raster layers. I set different elevations as Plane Height with the option Reference Plane �??below�?� to run this tool to get the volume of the targeted raster layers. The difference between two rasters is the volume of the unit rock as one raster is the top and the other is the bottom of the rock. You can see that the tool provides different volumes with varying elevations in the attached file (VolumeCalculation.xlsx). Instead of the option �??below�?�, the option �??above�?� the Plane Height (�??0�?�) was used to calculate the volume above. I am not sure which options such as Plane Height and Reference Plane (above or below) could provide precise result.
I did use the tool "Surface Difference" to process two TINs converted from two rasters. The processed result was still not precise since I can tell the resulting raster image only fits the small raster (Rock_Top) extent even after I specified the extent as the big raster (Rock_bottom). Even though the tool in 3D Analyst supports the Environments setting, �??Extent�?� (I also specified the Mask to big raster (Rock_bottom) in the "Raster Analysis").
The analysis can only work with the intersection of the extents, or the areas covered by both data sets. Otherwise, there are no constraints, and the values would go to infinity where there is no rock top to provide a stopping point. Regards, Jim
