Quantum GIS (QGIS) is a free and open-source software for geographical information system (GIS) usage. It is helpful to visualize and analyze Pix4D outputs.
Import of DSM / DTM
Simply drag and drop the .tif file into the main view of QGIS.
If multiple files have been imported, create a Virtual Raster to manage the digital surface model (DSM) / digital terrain model (DTM) files as one single file. For more information: QGIS help.
For more information about editing the classification of evaluation values, click here.
Contour lines from DSM / DTM
Pix4Dmapper can generate contour lines. For more information: Menu Process > Generate Contour Lines. However, it is also possible to extract contour lines using the digital surface model (DSM) or digital terrain model (DTM) generated by Pix4Dmapper.
1. Drag and drop the .tif file into the main view of QGIS.
2. On the menu bar, click Raster > Extraction > Contour...
Display of contour lines with elevation values
Note: Contour lines in the shapefile (.shp) format are required. They can be generated from the digital surface model (DSM) or the digital terrain model (DTM):
How to generate the contour lines.
1. Find the contour lines in 3_dsm_ortho/extras/contours.
2. Drag and drop the contour lines .shp file onto the main view of QGIS.
3. Right-click on the contour lines layer and click Properties.
4. Select the tab Labels.
5. From the drop-down list Label this layer with, select Elevation and ensure the box is checked.
The final result will have the contour lines along with the associated elevation values.
Merge of .tif orthomosaic / DSM / DTM files
When the area of interest is very big and the amount of data is large, multiple Pix4Dmapper projects can be created for one area. To merge .tif files that are generated from the multiple projects, use an external GIS software like Quantum GIS.
Important: The projects must be georeferenced with GCPs in order to have the same accurate georeference. For more information about the use of GCPs:
Step 1. Before Starting a Project > 4. Getting GCPs on the field or through other sources (optional but recommended).
In order to merge the different GeoTIFF orthomosaic files in Quantum GIS:
1. On the menu bar, click Raster > Miscellaneous > Merge.
2. In the field Input files, click Select, browse for the tiles to merge, select them and click Open (use the shift key in order to select all).
3. In the field Output files, click Select, set the name of the output mosaic / DSM and select the format GeoTIFF (*...). Choose where to export the new merged file and click Save.
4. (DSM only) check the box No data value and set it to -10000.
5. Check the box Load into canvas when finished in order to see the merged file once it is generated.
6. Click OK.
Conversion of GeoTIFF to georeferenced .jpg or .jpeg format
1. Drag and drop the GeoTIFF file onto the main view of QGIS.
2. On the menu bar, click Raster > Conversion > Translate (Convert Format)...
3. In the field Output File, click Select...
4. Enter a name and select the type of file JPEG.
5. Click Save.
6. In the window Translate (Convert Format), click OK.
Create an RGB composite
To make an RGB composite in QGIS:
1. Open QGIS and click .
2. Browse to the directory with the individual images. Hold down the Ctrl key and click on the image files to make a multiple selection. Click Open.
3. Create a single Mosaic image from all these individual images.
4. Click .
Note: To enable the
Raster menu in QGIS the core plugin called
GdalTools is needed. Enable the
GdalToolsplugin from:
.
QGIS Tutorial: http://www.qgistutorials.com.
QGIS Tutorial: http://www.qgistutorials.com.
5 .In the Merge dialog, click Select...
6. In the Input files browse the directory that contains all the individual geotiffs. Hold Ctrl key and select all the subsets.
7. Click Select... next to Output file and name the output.
8. Click OK...
Information:
Youtube Tutorial QGIS video working with Multispectral Bands:
Youtube Tutorial QGIS video working with Multispectral Bands:
Youtube video for Mac:
Youtube video on how to use the SAGA plugin in QGIS:
Disclaimer: Pix4D publishes this information as a courtesy to its customers. Pix4D makes no warranty of any kind, expressed or implied, with respect to the content's validity or accuracy.