Average Height of Points Above DEM
sktse
Global Mapper UserTrusted User
I have a DEM generated the previous year, and this year I've set of sample point elevations, and I'm trying to find out the average difference between the points and the elevation directly below each point.
I'm unsure of how to do this quickly and efficiently. Is there a good way to do this? Thanks!
I'm unsure of how to do this quickly and efficiently. Is there a good way to do this? Thanks!
Comments
-
There is probably more than one way to do this but here's the workflow that I came up with:
1. Using the Digitizer, select all of the points
2. Right-click anywhere on the map and choose EDIT- Edit Selected Features
3. Under Feature Attributes, use the drop-down list to select the existing elevation attribute
4. If this attribute is called "Elevation" click the Rename button and type Elevation1
5. Click the OK button
6. With the points still selected and the previous DEM layer visible, right-click on the map and choose Attribute/Style Functions > Apply Elevations from Terrain Layers to Selected Feature(s)
7. When prompted, click the No button to assign as new values
8. Use the Feature Info tool to verify that each point now has two elevation values
9. In the Overlay Control Center, right-click on the point layer and choose CALC ATTR - Calculate/Copy Attribute Value
10. In the Select Existing or Create New Attribute... field, type Elevation Difference
11. From the Source Attribute drop-down list, choose Elevation1
12. From the Operation list, choose Subtract
13. Select Use Attribute Value and select Elevation
14. Click the Calculate button and close the window
15. Use the Feature Info tool to verify that each point now has an elevation difference value
16. Open the Search Vector Data dialog box (binoculars button in the toolbar)
17. With your cursor anywhere in the Elevation Difference column, right-click and choose STATS - Report Statistics for Values or "Elevation Difference" The resulting window will display the average of the values in this attribute field.
I hope this helps.
- David McKittrick
Senior Applications Specialist
Blue Marble Geographics -
Thank you very much for this!DMcKittrick wrote: »There is probably more than one way to do this but here's the workflow that I came up with:
1. Using the Digitizer, select all of the points
2. Right-click anywhere on the map and choose EDIT- Edit Selected Features
3. Under Feature Attributes, use the drop-down list to select the existing elevation attribute
4. If this attribute is called "Elevation" click the Rename button and type Elevation1
5. Click the OK button
6. With the points still selected and the previous DEM layer visible, right-click on the map and choose Attribute/Style Functions > Apply Elevations from Terrain Layers to Selected Feature(s)
7. When prompted, click the No button to assign as new values
8. Use the Feature Info tool to verify that each point now has two elevation values
9. In the Overlay Control Center, right-click on the point layer and choose CALC ATTR - Calculate/Copy Attribute Value
10. In the Select Existing or Create New Attribute... field, type Elevation Difference
11. From the Source Attribute drop-down list, choose Elevation1
12. From the Operation list, choose Subtract
13. Select Use Attribute Value and select Elevation
14. Click the Calculate button and close the window
15. Use the Feature Info tool to verify that each point now has an elevation difference value
16. Open the Search Vector Data dialog box (binoculars button in the toolbar)
17. With your cursor anywhere in the Elevation Difference column, right-click and choose STATS - Report Statistics for Values or "Elevation Difference" The resulting window will display the average of the values in this attribute field.
I hope this helps.
- David McKittrick
Senior Applications Specialist
Blue Marble Geographics
Categories
- 12.7K All Categories
- 5.6K Features Discussion
- 342 Downloading Imagery
- 1.3K Elevation Data
- 380 Georeferencing Imagery Discussion
- 627 GM Script Language
- 52 User Scripts
- 113 GPS Features
- 414 Projection Questions
- 819 Raster Data
- 1.3K Vector Data
- 6.6K Support
- 177 Announcement and News
- 908 Bug Report
- 558 SDK
- 1.2K Suggestion Box
- 3.7K Technical Support
- 562 Other Discussion
- 129 GIS Data Sources
- 27 Global Mapper Showcase
- 233 How I use Global Mapper
- 107 Global Mapper Forum Website