I have a massive dataset consisting of 500,000+ (sometimes pushing 1 million) individual small triangular polygons that are generated by exporting overland flow results out of a two-dimensional hydraulic model. This is the native export format of this software, no option to export to grid/raster.
The native dataset takes forever to redraw, as you might imagine.
I want to dissolve these triangle into ranges of depth...say 1 large polygon containing all individual triangles that are between 0.1-0.5 feet deep, and another single large polygon containing all individual triangles between 0.5-1.0 foot deep, and so on...so that I end up with a total of, just say, 5 (1 per each depth range, however many ranges I want) discreet large polygons that represent all the smaller, individual constituent polygons within each range.
I've tried, dissolve, merge, select by attributes>dissolve, and a few other off the wall ideas and nothing seems to work. I get either a "Invalid Topology" error or GIS just drops (loses, deletes) large volumes of data in the process.
Here is an example of what I am talking about...
This is what the results look like natively. The red is depths greater than 1.0 feet, the green is less than 0.5 feet, and the yellow is in between.
[ATTACH=CONFIG]34579[/ATTACH]
Then when I try to dissolve everything that is deeper than 1.0 foot, for example, (it SHOULD give me one single polygon the same extents as all the red) I get the choppy blue triangles...not at all what I was expecting.
[ATTACH=CONFIG]34580[/ATTACH]
Can somebody point out where I am going wrong?
Thanks. -JW
