Exercise: Estimating top height of a forest stand by airborne laser scanning (ALS)
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# In the ''Data Source'' window navigate to the path ''.\GBData\ALS'', double click on the digital terrain model ''dtm_abt49b1.sgrd''. The DTM in raster format was derived from the last pulse of ALS point data. Double click on the layer ''dtm_abt49b1'' in the ''Workspace'' to open a new viewer. In the properties of the layer dtm_49b1 on the right side of the Gui click the checkbox ''Show Cell Values'' on. | # In the ''Data Source'' window navigate to the path ''.\GBData\ALS'', double click on the digital terrain model ''dtm_abt49b1.sgrd''. The DTM in raster format was derived from the last pulse of ALS point data. Double click on the layer ''dtm_abt49b1'' in the ''Workspace'' to open a new viewer. In the properties of the layer dtm_49b1 on the right side of the Gui click the checkbox ''Show Cell Values'' on. | ||
# Double click on the boundary of the stand compartment 49b1 ''boundary_abt49b1.shp'' in vector format. Double click on the Polygon layer boundary_abt49b1 in the ''Workspace''. The stand polygon is displayed on top of the digital terrain model. On the right side of the GUI change the layer properties of boundary_abt49b1: Fill style: Transparent, Outline color white. # Activate {{button|text=Zoom}} [[file:SAGA_zoom.png|25px]] and left click several times into the viewer to see height above sea level as digital value of every raster cell. | # Double click on the boundary of the stand compartment 49b1 ''boundary_abt49b1.shp'' in vector format. Double click on the Polygon layer boundary_abt49b1 in the ''Workspace''. The stand polygon is displayed on top of the digital terrain model. On the right side of the GUI change the layer properties of boundary_abt49b1: Fill style: Transparent, Outline color white. # Activate {{button|text=Zoom}} [[file:SAGA_zoom.png|25px]] and left click several times into the viewer to see height above sea level as digital value of every raster cell. | ||
| − | # {{button|text=Zoom to full extent}} [[file:SAGA_zoomFull.png|25px]] {{button|text=Show 3-D view}}. Select the grid system ''1:469x 685y and Elevation: ''dtm_abt49b1''. Change the display resolution to 1000. {{button|text=OK}}. Left click in the 3D viewer and hold to move the 3D perspective. | + | # {{button|text=Zoom to full extent}} [[file:SAGA_zoomFull.png|25px]] and then {{button|text=Show 3-D view}} [[file:SAGA_3DView.png|25px]]. Select the grid system ''1:469x 685y and Elevation: ''dtm_abt49b1''. Change the display resolution to 1000. {{button|text=OK}}. Left click in the 3D viewer and hold to move the 3D perspective. |
# Toggle the {{button|text=Anaglyph}} [[file:SAGA_Anaglyph.png|25px]] and put on stereo glasses with red for the left eye and cyan for the right side to see the 3D effect. (Fig. '''B'''). | # Toggle the {{button|text=Anaglyph}} [[file:SAGA_Anaglyph.png|25px]] and put on stereo glasses with red for the left eye and cyan for the right side to see the 3D effect. (Fig. '''B'''). | ||
Revision as of 15:21, 17 July 2014
Contents |
Study site
Several aerial missions equipped with airborne laser scanner (TopoSys Falcon II, Riegl LMS-Q560) and airborne digital camera (TopoSys line scanner, DLR HRSC-A) were flown in two forest districts in Northrhine-Westfalia in the years 2004-2007. The study sites Glindfeld (76km2) and Schmallenberg (280km2) are located in the low mountain range Sauerland in Northrhine-Westfalia, Germany. Main economically important tree species are spruce (Pices abies) and beech (Fagus sylvatica).
Displaying digital orthophotos (DOP)
- Start SAGA GIS Start --> All Programs --> OSGeo4W --> SAGA GIS. If you do not find this link start the windows explorer, navigate to the folder C:\OSGeo4W\apps\saga. Copy the file
saga_gui.exe and paste as a link on the desktop. Double click on the link symbol to start SAGA GIS.
- Find the file browser in the Data Source window in the the lower left of the SAGA Gui. Navigate to the path .\GBData\ALS where you saved the uncompressed tutorial data. Double click on the files so_abt49b1-Composite.sgrd, wi_abt49b1-Composite.sgrd and PCA-Composite.sgrd. Click on the Data Tab of the 'Workspace' window. Double click on the first loaded layer to open a viewer window. Continue with the second and third layer and confirm always Map Selection New to open new cascaded viewer windows. Rearrange the viewers Window --> Tile vertically and link the viewers geometrically Map --> Synchronise Map Extent.
- Activate a layer by marking the layer in the Workspace 'Data' tree. On the right side of the GUI is a window displaying the layer properties. Under Colors change the Type from Graduated color to RGB. Click Apply and repeat these steps for the other two layers (Fig. A). Place the cursor in one of the viewers. Zoom in with a left click and zoom out with a right click. Activate Pan
to move the images. Describe the characteristics to distinguish the main tree species spruce and beech.
Displaying digital terrain model
- In the Data Source window navigate to the path .\GBData\ALS, double click on the digital terrain model dtm_abt49b1.sgrd. The DTM in raster format was derived from the last pulse of ALS point data. Double click on the layer dtm_abt49b1 in the Workspace to open a new viewer. In the properties of the layer dtm_49b1 on the right side of the Gui click the checkbox Show Cell Values on.
- Double click on the boundary of the stand compartment 49b1 boundary_abt49b1.shp in vector format. Double click on the Polygon layer boundary_abt49b1 in the Workspace. The stand polygon is displayed on top of the digital terrain model. On the right side of the GUI change the layer properties of boundary_abt49b1: Fill style: Transparent, Outline color white. # Activate Zoom
and left click several times into the viewer to see height above sea level as digital value of every raster cell.
- Zoom to full extent
and then Show 3-D view 
. Select the grid system 1:469x 685y and Elevation: dtm_abt49b1. Change the display resolution to 1000. OK. Left click in the 3D viewer and hold to move the 3D perspective.
- Toggle the Anaglyph
and put on stereo glasses with red for the left eye and cyan for the right side to see the 3D effect. (Fig. B).
