Is there a free desktop utility to batch process say 4,000+ points that currently have ellipsoid heights and need to be converted to orthometric heights? I realize there are tools to accomplish this task one by one, but probably out of the questions here.
I am currently downloading a demo version of [REDACTED]'s Geographic Calculator to test it's capabilities and may have to purchase a copy as a last resort.
Any help would be appreciated. Thank you.
Brett
> Is there a free desktop utility to batch process say 4,000+ points that currently have ellipsoid heights and need to be converted to orthometric heights? I realize there are tools to accomplish this task one by one, but probably out of the questions here.
>
> I am currently downloading a demo version of [REDACTED]'s Geographic Calculator to test it's capabilities and may have to purchase a copy as a last resort.
>
> Any help would be appreciated. Thank you.
>
> Brett
Why not just write a spreadsheet?
If you just want to model them with a geoid then Corpscon will do the trick. I've never ran 4000 points through it at once though.
http://www.agc.army.mil/corpscon/index.html
Geoid09 takes some fiddling with to get it into Corpscon, but the link below explains it well.
http://www.agc.army.mil/corpscon/CORPSCON-n-Geoid09.pdf
Thank you for the responses so far.
I have 4,000 manhole lids collected with a GIS data collection software that only measures the ellipsoid height, but the end result needs to be an orthometric height. The projection file is in state plane coordinates, so I assume with any batch software I will have to convert the stated plane coordinates to geographic coordinates to get the software to properly convert the file.
At the end of the day I am looking for an easy way to take the ellispoid heights and convert them into orthometric heights. Ideally this would be using Geoid 09.
I will try to play with Corpscon, but I thought it would only do a single point at a time, not a file to process.
There is no upper limit on the number of points that you can “batch process” in GEOID09 (or if there is it's pretty LARGE). I have processed over 25 MILLION points at a time, and although it takes a little while, it doesn't require any “supervision.”
Simply download GEOID09 and the requisite Grid files for you area.
Convert your spc values, ellipsoid heights, points numbers, and station descriptions to “TYPE-2” files (see examples in the GEOID09 reference material), and pull the trigger.
When it's done chewing on the data, transform GEOID09 output file to whatever format you need (and projection you need), applying the 'N' values in the process.
Loyal
> I will try to play with Corpscon, but I thought it would only do a single point at a time, not a file to process.
The option is under the "Convert" pull-down...
It doesn't need any more memory to do one point or 50 million. It is reading them one at a time, so it just takes some time.
Corpscon should do the trick.
For my area this wouldn't work very well, but you could check what the typical Geoid seperation is in your area. It may be that you have a consistent number across the site and you can just add (the elevation is a larger number than the height) a factor to your height to get the elevation.
By saying you are using a GIS data collector I take it that this isn’t survey grade information (+-0.1-0.2’). Curiosity got the better of me and I did a quick check of the geoid numbers at Iowa City. NW part of the city +106.8' (that's a large number), the center of town +106.9' and the SE part of town +107.0'. So, if you don’t have numbers that are accurate to start with, I’d just get the geoid numbers for a few points across the project and if they look consistent I’d do a + (using an average) to all the points.
Now, if the data is survey grade then run it through Corpscon. It will probably take a bit to learn it, I've used it before with large files and it would handle 4000 points no problem. But that was years ago, before I had GPS.
> I have 4,000 manhole lids collected with a GIS data collection software that only measures the ellipsoid height
I hope that whatever report accompanies the numbers will include a note on the accuracy of the resulting ortho heights. GIS-grade observations + geoid model = close enough to pick out the contour line, but not much else.
The software is GIS data collection software, but the unit is a survey grade.
> > I have 4,000 manhole lids collected with a GIS data collection software that only measures the ellipsoid height
>
> I hope that whatever report accompanies the numbers will include a note on the accuracy of the resulting ortho heights. GIS-grade observations + geoid model = close enough to pick out the contour line, but not much else.
I've always been led to believe that if one wants good elevations (ortho) on a gps point one has to be surrounded by gps points that are on known ortho heights. Have things changed?