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Update LidarProcessing.rst
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biglimp committed Nov 8, 2023
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49 changes: 19 additions & 30 deletions docs/source/Tutorials/LidarProcessing.rst
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Expand Up @@ -170,8 +170,8 @@ Now you can use all the executable algorithms that are available in the
**C:\\FUSION\\**. Try by typing **gridsurfacecreate**. Now you will see
the documentation available for this specific algorithm. As you want to convert your **.dtm** file you will make use of **DTM2ASCII**. Type the
following command:

**dtm2ascii /raster ground.dtm**
::
dtm2ascii /raster ground.dtm

You have now created an ESRI ASCII grid (in the same folder as
**ground.dtm**) that you now can open QGIS. Open **ground.asc** in QGIS.
Expand All @@ -191,10 +191,8 @@ the command prompt, **PolyClipData**. The algorithm is used to
separate out certain points from the point cloud. Remove **by\_get.shp**
from your QGIS project if the layer is loaded. Locate yourself in the
**LaserData** folder and enter the following command in one line:

**polyclipdata /outside /class:1
“c:\\temp\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp”
“c:\\temp\\LidarQGISFUSION\\Output\\veg.las” “gvc.las”**
::
polyclipdata /outside /class:1 “c:\\temp\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp” “c:\\temp\\LidarQGISFUSION\\Output\\veg.las” “gvc.las”

Sometimes the folder paths malfunction. If you get an error
message, try copying the **by\_get.shp** in the same folder as
Expand Down Expand Up @@ -249,9 +247,8 @@ want to filter out lower points that can be, for example, people or cars. To do
the algorithm of running it from the *Processing Toolbox* so we need
to run it from the command prompt. Locate your folder *Output* and enter
the following:

**clipdata /ground:ground.dtm /zmin:2.5 veg.las veg\_filt.las 318864.0
319364.0 6397926.0 6398400.0**
::
clipdata /ground:ground.dtm /zmin:2.5 veg.las veg\_filt.las 318864.0 319364.0 6397926.0 6398400.0

This was done to exclude all the points that are lower than 2.5 meters
from our ground model (**/zmin:2.5**). The coordinates at the end are
Expand All @@ -275,13 +272,9 @@ lot of "holes", there are also occasional lamp posts, etc. Plus the buildings in
how the **CanopyModel** algorithm works. You can read more about this
in the manual if you are interested. Let's start by removing buildings.
To do this, create a new polygon layer by buffering the building
footprint layer (**by\_get.shp**) by 2 meters (*Vector > Geoprocessing Tools > Buffer*). Set *End cap style* to *Flat* and *Join style* to *Miter*. Name your new shapefile
**by\_buff.shp** and save it in the folder **Fastighetskartan**. We must
also create an additional attribute for **by\_buff.shp** with the value
0. Open the *attribute table* and then the *Field Calculator*
(abacus). Configure the following settings (Figure 11) and click OK. Then
save and close the editor mode (buttons to the top left of the attribute
table).
footprint layer (**by\_get.shp**) by 2 meters (*Vector > Geoprocessing Tools > Buffer*). Set *End cap style* to *Flat* and *Join style* to *Miter*. Name your new shapefile **by\_buff.shp** and save it in the folder **Fastighetskartan**. We must also create an additional attribute for **by\_buff.shp** with the value
0. Open the *attribute table* and then the *Field Calculator* (abacus). Configure the following settings (Figure 11) and click OK. Then
save and close the editor mode (buttons to the top left of the attribute table).

.. figure:: /images/Lidar11.jpg
:alt: none
Expand Down Expand Up @@ -311,8 +304,8 @@ Therefore, we need to remove these values from the vegetation raster.
This can be done in the *Raster Calculator* in QGIS. Open *Raster
Calculator* and choose write the following expression in the *Raster
Calculator Expression* Window:

**(cdsm\_filt@1 > 0.5) \* cdsm\_filt@1**
::
(cdsm\_filt@1 > 0.5) \* cdsm\_filt@1

Call the output file **cdsm\_filt2.tif** and save as a geoTIFF.

Expand Down Expand Up @@ -376,8 +369,8 @@ This is about as far as you can come with a point cloud like this. Bare soil is
Merging into on land cover grid
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Make use of the *Raster Calculator* again using the following syntax:

**("build_bolean@1") + ("lc_bolean@1" * 2) + (("build_bolean@1" * "veg_bolean@1") * 3)**
::
("build_bolean@1") + ("lc_bolean@1" * 2) + (("build_bolean@1" * "veg_bolean@1") * 3)

Call the output **landcover_raw.tif**.

Expand All @@ -397,20 +390,16 @@ Commands
--------

To add an environment path in the command prompt:

**Path %PATH%;C:\\FUSION**
::
Path %PATH%;C:\\FUSION

To cut out laser points within building footprints:

**polyclipdata /class:1**
**”c:\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp” ”buildings.las”**
**”gvc.las”**
::
polyclipdata /class:1 ”c:\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp” ”buildings.las” ”gvc.las”

To cut out laser points on the ground:

**C:\\LidarQGISFUSION\\Laserdata>polyclipdata /outside /class:2**
**”c:\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp” ”ground.las”**
**”gvc.las”**
::
C:\\LidarQGISFUSION\\Laserdata>polyclipdata /outside /class:2 ”c:\\LidarQGISFUSION\\Fastighetskartan\\by\_get.shp” ”ground.las” ”gvc.las”

References
----------
Expand Down

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