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Visualize LiDAR LAS file in SAGA GIS
SAGA GIS is a free open source software package that I find
useful for performing GIS grid analysis on raster data. The latest
version 2.0.5 has some functions to read and write LiDAR LAS files
including visualizing the LiDAR point clouds in 3D. Unlike other
LAS file viewers where you simply choose the LAS file to display,
there is a two step process involved when using SAGA to view LAS
files. First, the LAS file has to be imported into SAGA's point
cloud format. Once that is completed, you can then view the data
either in 2D or 3D depending on the function you choose. Import LAS
file into SAGA GIS
1. On the Windows desktop, choose Start | All Programs | SAGA
GIS. The SAGA GIS application appears.
2. Select Modules | File | Shapes | Import | Import LAS
Files.
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The Import LAS Files dialog box appears.
3. Click the Input File row. Then click the browse button on the
right side. Browse and
choose a LAS file. Click Open. The selected file name is
displayed in the Input File row.
4. Under the Attributes to import besides x,y,z list box, toggle
on any attributes to be imported e.g. intensity. Click Okay. The
LAS file is imported into SAGA GIS as a point cloud data set. Note:
it may be necessary to click the Data tab on the Workspace
pane.
Visualizing the LiDAR point cloud
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1. Select Modules | Shapes | Point Clouds | Visualization |
Point Cloud Viewer. The Point Cloud Viewer dialog box appears.
2. Click the drop down list on the right of the Points row.
Choose the LiDAR point
cloud data to visualize. The selected point cloud is
displayed.
3. Click Okay.
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The point cloud is displayed in the Point Cloud Viewer.
Using the Point Cloud Viewer
1. To zoom in the main 3D view, roll the mouse wheel backwards.
2. To zoom out in the main 3D view, roll the mouse wheel forward.
3. To pan, press down the right mouse button and drag in the
desired direction. 4. To view a smaller subset of the point cloud,
press down the left mouse button and
drag out a subset box in the overview map on the bottom left.
Then release the mouse button. Only the subset is displayed in the
main 3D view.
5. To freely rotate the 3D display in 3D, simply move the mouse
over the 3D view and
press down the left mouse button and drag in the direction you
want to rotate.
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6. To change the display colors or other settings, click
Advanced Settings. The Point Cloud Viewer Settings dialog box
appears.
7. To change the point colors, click the Colors row. Then click
the [...] button on the
right. The [CAP] Colors dialog box appears.
8. Use the buttons to change the colors. Or click Presets to use
preexisting schemes.
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The Preset Selection dialog box appears.
9. Choose a scheme e.g. greyscale for coloring intensity points.
Click Okay.
The [CAP] Colors dialog box is updated.
10. Click Okay. Then click Okay again to close the Point Cloud
Viewer Settings dialog
box. The 3D display is updated with the new settings.
11. To color the points by another attribute other than the
elevation e.g. intensity, click the Color Attribute drop down list
and choose another attribute such as intensity.
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The 3D display is updated.
12. To scale the points larger nearer to the viewing point, and
smaller further away, toggle
Scale Point Size on.
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13. To render for stereo red/blue glasses, toggle Anaglyph
on.
Original post :
http://dominoc925.blogspot.com/2010/07/visualize-lidar-las-file-in-saga-gis.html