Adding 3D object to elevation dataset
I have a seabed model (undulating surface) to which I'd like to add a 3D object (in this case, to model rock berms). The rock berms are essentially a frustum ("3d trapezium").
The elevation data is xyz to created a DTM. The rock berms I'd like to model are either:
1) Constant height above seabed
2) Constant elevation (i.e., variable height relative to seabed).
Is this possible to do in Global Mapper? Can anyone please share if done before, or perhaps suggestions to try.
Initially thought to build the rock berm in another software & import into GM - however a) trying to avoid multiple software b) not sure if it will "account" for actual seabed as eventually want to estimate the volume of 3d berm.
Simple answer is yes you can do exactly what you are asking in GM, although probably too many steps to explain here in detail. I have done exactly what you are trying to do, but on land/above sea level to design rock bunds, road embankments, cuttings, pits, stockpiles etc. although that shouldn't make any difference as you just working with vectors and a DTM.
To do both 1) and 2) above you need to create or import your berm centreline and make sure to "Update Elevations from Terrain" i.e. the centreline vertices elevations match the terrain elevation, as shown below:
For 1), if the berm had say a 50 m wide crest, say, I would select the centreline, then right click and select "Advanced Feature Creation Options" and then " Buffer" and then buffer the centreline on both sides at 25 m and if I wanted crest to be fixed at 10 m above seabed, say, I'd add 10m to "Offset z value of 3D buffers" as per screengrab below.
Then I'd select the 50 m wide bund crest "buffer" that I've just created and select "Calculate Flattened Site Grid.." and add bund side slopes (e.g. 26.6 deg fill & 45 deg cut), to create your "Constant Height" bund as per below:
For 2). Constant elevation when you create your berm crest buffer then select it and edit the vertex elevations to whatever elevation you want, in this example I have selected 510.0 mRL:
Then repeat as per final step for 1). i.e. select the 50 m wide bund fixed elevation crest "buffer" that you've just created and select "Calculate Flattened Site Grid." and add bund side slopes (e.g. 26.6 deg fill & 45 deg cut), to create your "Fixed Elevation" bund as per below::
You can then use the built-in tools in GM to extract cut/fill volumes, compare surfaces etc. and export to AutoCAD, Excel etc.
If you haven't already, I strongly suggest you watch these two GM YouTube training videos on Terrain Analysis (sorry I wasn't able to insert the URL for some reason???, so just screen snipped them below).
Hope this helps.
Thanks for the detailed response. Good to hear it can be done! Will give this a go.
Apologies for the delay in responding, got really busy! I've tried the above & works a treat! Thanks again for your post, very helpful & much appreciated.
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