Another 'Hey Wow, That's Cool' moment
I've been playing with some recent updates to the New Zealand DEM and DSM data.
I'm well impressed with the level of detail.
From National to Local, it looks great
What's the difference between DSM and DEM ?
Thank you Land Information New Zealand
What's the difference between DSM and DEM ?
DSM should include man-made features as well (i.e. building as shown in mid right side of your picture). Also note the tree heights are kind of visible.
DEM is 'bare' earth although surface features do show up to some extent, they are not as well defined (you can tell something is there in the second picture, but it is not clearly a building).
DTM is another one and it would be similar to DEM but features that create break lines, such as streams, are more defined.
@jon-payne That seems so unnecessarily confusing. Maybe someday there will just be 1 with maximum detail that everyone uses.
@bstrand Some don't understand the nuance between DSM, DEM and DTM, but that's not too different than the "nuance" between Astronomic North, True North and Geodetic North.
Many years ago, I created a "DEM" for 1100 sq.km. in a west African nation. I utilized the French Pleiades satellites and a pair of high-end software packages to process four stereo pairs and created a 1-meter DEM from them using ground control points established by a local survey firm with RTK.
I mosaicked the four "DEMs" into a final DSM (digital surface model). I thought I was done until the mining company said that the "DEM" needed to be a bare earth model so that another consultant could create a surface water model of the area. I bought a LiDAR software package with digital feature extraction. After some test runs, I created an idealized tree feature on the DSM. Running the software in 12 batches I ended up removing a smidge over 39,000,000 trees to create a DTM (digital terrain model) that the surface water modelers were able to use to good effect.
Some don't understand the nuance between DSM, DEM and DTM, but that's not too different than the "nuance" between Astronomic North, True North and Geodetic North.
Sometimes it's just semantics, eg, what's "True North" in your statement and which of those (if any) could also be called Magnetic North? I've thought that there are 4 norths - Magnetic, geodetic, astronomic and grid. And that "true north" ends up being just one of them that the author perceives as true or is has the most personal experience with (or they're lazy).
@dave-o And the fifth north Assumed.