| Re: difference between DEM and DSM [message #71985 is a reply to message #71982] |
Fri, 30 July 2010 10:52   |
Ben Kamphaus
Messages: 3
Registered: July 2010
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Junior Member |
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Yeah, the DSM is the easy one if you're working with a LiDAR point
cloud, for example. To create the DSM you'll just interpolate the
elevation values at each point to a grid. The DEM/DTM extraction
(also called bare earth extraction) requires some sort of
morphological filtering process to be applied to either the DSM or the
point cloud. If the filter operates on the DSM, it removes outlier /
feature values and replaces them with interpolated values to preserve
the morphology of the ground values. If the filter operates on the
point cloud, it will sort the points into ground and non-ground then a
separate interpolated grid will be calculated from only the ground
points.
On Jul 30, 11:43 am, Mort Canty <m.ca...@fz-juelich.de> wrote:
> Am 30.07.2010 16:52, schrieb skymaxw...@gmail.com:
>
>> Good day !
>
>> I want create digital elevation model (DEM) and digital surface
>> model(DSM) by IDL.
>> I know how to do DEM, but how build DSM ?
>> What data required to build it and what theory ? Any links to read
>> about this subject will appreciate.
>
>> Thanks
>
> Wikipedia?
>
> A digital elevation model - also sometimes called a digital terrain
> model (DTM) - generally refers to a representation of the Earth's
> surface (or subset of this), excluding features such as vegetation,
> buildings, bridges, etc. The DEM often comprises much of the raw
> dataset, which may have been acquired through techniques such as
> photogrammetry, LiDAR, IfSAR, land surveying, etc. A digital surface
> model (DSM) on the other hand includes buildings, vegetation, and roads,
> as well as natural terrain features. The DEM provides a so-called
> bare-earth model, devoid of landscape features. While a DSM may be
> useful for landscape modeling, city modeling and visualization
> applications, a DEM is often required for flood or drainage modeling,
> land-use studies, geological applications, and much more.
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