Terrains, TINs, Lidar
redbeard
Global Mapper UserTrusted User
Since I use GM for it's strong elevation support...I thought this might be a good place.
Esri has something called a terrain dataset - not sure if GM can read them or not, but they look neat.
From that (and not esri specific)...
1) is there a way to "decimate" the TINs, and create pyramids or multiple resolution TINs in GlobalMapper?
The other idea
2) Lidar data often needs a bounding polygon/line/breakline to help create TINs in whatever system you choose, but often does not come with any. Is there a way to automatically create a nice polygon to use for this purpose? As I read some of the meta in these datasets, it seems you should be able to with some analysis - perhaps a buffer of all the points with the distance being some factor relating to density of the points.
Another way would be to somehow connect all the "outer" dots together, thus forming a 3d polyline around the perimeter. I guess the definition of outer could depend on average distance between points (often found in the meta).
Just two ideas.
Esri has something called a terrain dataset - not sure if GM can read them or not, but they look neat.
From that (and not esri specific)...
1) is there a way to "decimate" the TINs, and create pyramids or multiple resolution TINs in GlobalMapper?
The other idea
2) Lidar data often needs a bounding polygon/line/breakline to help create TINs in whatever system you choose, but often does not come with any. Is there a way to automatically create a nice polygon to use for this purpose? As I read some of the meta in these datasets, it seems you should be able to with some analysis - perhaps a buffer of all the points with the distance being some factor relating to density of the points.
Another way would be to somehow connect all the "outer" dots together, thus forming a 3d polyline around the perimeter. I guess the definition of outer could depend on average distance between points (often found in the meta).
Just two ideas.
Comments
-
If the Esri terrain data set is just their Arc Binary Grid or Arc ASCII Grid, then you can load in either one.
You can export out terrain to a format like Global Mapper Grid and it will automatically have multiple zoom resolutions based on the specified export resolution. There isn't really a way to do that right from TINs, although you can of course grid the TIN and then work on it like any other grid data set.
For gridding Lidar data, use the grid tightness slider and move it towards the "tight" side to get a grid generated just near the actual data. You can also create a convex hull boundary polygon when gridding.
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
Not quite. Their terrains are vector format, in which people might derive a raster product from it.
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/What_is_a_terrain_dataset/005v00000002000000/
http://www.esri.com/news/arcuser/0311/terrain-datasets.html
I was just wondering if GlobalMapper could do something similar. Not necessarily create the esri product, but whatever format, though I do prefer a more open format than closed (another TIN, or maybe something like a global mapper package except for vector).
Basically their low resolution TINs(pyramids) are derived from a subset of lidar points, with some z tolerance setting.
Does that make sense? -
Ah ok now I can see what it is. It looks like that type of terrain database is typically stored in an Esri File Geodatabase. While Global Mapper can read some vector data from that format through an Esri-supplied API, they do not supply support for reading terrain (or raster) data. In general the concept is a multi-resolution TIN. This is not currently support for generating multi-resolution TINs in Global Mapper, just multi-resolution gridded surfaces (like via a GMG file).
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
perhaps in the future we could see a .gmt - global mapper terrain/tin?
But all that being said - I'm just starting to try and figure out a way to manage lidar data as it can be quite a lot of data to manage. I do like GMG, but I do want access to the original data/values at the same time. -
Eventually there might be a special TIN-based format, perhaps once Global Mapper actually uses TINs for something other than an intermediate for creating grids from 3D vector data.
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com
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