Hello friends,
i have two DTMs and two DSMs created from LAS files......
first LAS files were created in autumn
second LAS were created in spring
when i compare elevations between DTM autumn and DTM spring.......differences are minimal, but to and fro are big differences, like -50 metres
same at DSMs..
what could have caused it? may it be caused by noise by scanning or even something else?
thank you so much
Sorry, I am not with you here.
When you say "differences are minimal, but to and fro are big differences, like -50 metres",
is this a difference between the surveys or a difference between the DEM (ground surface) and DSM (includes structures)?
between the surveys in autumn and spring
Well 50m is a lot. Are these from 2 different survey companies?
There is a possibility that one has supplied ellipsoidal heights and the other geoidal.
Better get back to the supplier to check.
Did they use some local control for their ht measurements?
no they are from one company
that deviations are somewhere in one pixel ....somewhere in two.....can it be caused by noise?
what is the cell size?
what about looking at the raw LAS data?
-cell size is 0,5
-can´t see raw las data ...don´t have access to do that
cell size of 0,5 what, inches or miles or ?
🙂
or maybe ,50 not -50 Steve
0.5 meters