I need a software that will break a topo survey up into squares of any size, say 25-feet square and give me the lowest elevation shot in each 25-foot square. Does anyone know of a macro or software that will do this?
I don't think Carlson does--or does it?
I don't know...
I would try with GlobalMapper...Elevation grid (25' cell) to xls...some kind of parse based upon x and y...for min. z?
Send me a TIN/DEM/XYZ...
I'll take a look...
DDSM:'(
If you have a coordinate list I think you could do this with Excel. Separate.by coordinates (squares) then sort lowest to highest.
i would wonder if carlson could do it via the surface -> grid
if the software will not do it directly, run a smaller grid, then work it back
now i am curious why you would need the low point in every regular shape
removing scan data for everything above the lowest elevation, thus reducing to bare earth contour.
> I need a software that will break a topo survey up into squares of any size, say 25-feet square and give me the lowest elevation shot in each 25-foot square. Does anyone know of a macro or software that will do this?
>
> I don't think Carlson does--or does it?
I was able to get promising preliminary results with the following process:
1. From the Carlson Civil menu, click Surface -- Modify Grid File -- Grid File Utilities.
2. Click the Select Grid(s) button to load a Carlson GRD file (or optionally click the Import Grid button to bring in data from an external source, e.g. TIN).
3. Click the Change Resolution button to establish a new sampled grid cell dimension (e.g. 25'x25').
4. Click on the Spreadsheet button to display the elevations of the grid in an internal spreadsheet control.
5. Click on the upper leftmost row/column header cell to select the entire contents of the internal spreadsheet control and press Ctrl+C to copy the contents to the Windows Clipboard.
6. Start up something like Microsoft Excel and when in a blank worksheet, press Ctrl+V to paste the contents of the Windows Clipboard into Excel. Presume for the sake of example that the "upper left" cell of data occurs in cell C8.
7. In a new worksheet (recommended), navigate to cell C8 and set its value to a formula along the lines of =MIN(Sheet1!C8,Sheet1!C9,Sheet1!D8,Sheet1!D9)
8. Drag the formula to cover the entire range of your data and you should get the lowest elevation shot in each 25-foot square. I hope this helps.
> removing scan data for everything above the lowest elevation, thus reducing to bare earth contour.
My colleague in Colorado recorded a short 8-minute video demonstrating bare earth extraction from scan data and dumping the results to a Carlson TIN. In the video, he used Carlson Point Cloud to perform the work.
Ladd,
Yes, I think that will work.
I decided to make an Excel Macro that does the same thing. Once I got started it was much easier to do than I thought. I turned it into a double sort, and then incremented the elevation search on 0.01 increments until one matched. That way I did not have an overly complex sort going on.
It simply looks for min x,y and max x,y in the grid square. Any coordinate that falls in that gets tagged, and then grouped, and then search starts at 0.00 and increments upward until one matches or is exceeded. The result is printed on the next workbook sheet.
Hardest thing was making the grids, but once that is figured out it is just searching to see if a point matches, then increment elev from zero. Worked it out on a 5x5 matrix. I guess it will work on a large scale.
