24. TIPS FOR CHECKING ELEVATION DATA

[jovivier]

To help you locate any errors in imported elevation data here are some quick tips:

1. You can use Delete Type to delete erroneous contours or spot heights. If you have elevations at zero (where this is incorrect) or at the Irricad ‘no elevation’ value of -3280000ft (-1000000m), simply use Select All, then action Delete Type and click on a ‘bad’ contour or spot height. Match on “Height” and all contours or spot heights with the same height will be deleted (Note this must be done separately for contours and spot heights).

2. A great way to check for errors in the imported elevation data is by using Tools|Highlight Elevations, where IRRICAD will colour code the highest through to the lowest elevations. This will show up any obvious errors in the data.

3. The 3D DEM View found in the Reports menu will also show up even small errors in the imported elevation data.

4. Running Design|Calculate Elevation Errors will show the maximum error between the elevation inputs and the surface of the calculated DEM (see below). If the error is significant, click on the coordinate link to take you to that location. This method typically shows up inconsistencies in the elevation data, such as crossed contours or doubled spot heights. These problems can be fixed by deleting the erroneous data point(s). You may repeat this until the maximum error reported is acceptable, or check Reports|View Errors to see a list of the ten largest elevation errors.

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We hope you have found this helpful. If you have a tip you would like to share, please email your tip to Support@IRRICAD.com