Skip to content

Georeferencer updates #9759

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
DelazJ merged 5 commits into from
Apr 17, 2025
Merged

Georeferencer updates #9759

Show file tree
Hide file tree
Changes from 4 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
5e03fed
Georeferencer updates
selmaVH1 Apr 3, 2025
6f3e3a9
Transformation settings update
selmaVH1 Apr 3, 2025
13754e1
Remove unnecessary explanations
selmaVH1 Apr 16, 2025
40f20c1
Georeferencing vector section
selmaVH1 Apr 16, 2025
b5709f5
small title fix
selmaVH1 Apr 17, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion docs/user_manual/introduction/qgis_configuration.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -524,7 +524,7 @@ support read and write access:

* :guilabel:`Edit create options`: allows you to edit or add different profiles
of file transformation, i.e., a set of predefined combinations of parameters
(type and level of compression, blocks size, overview, colorimetry, alpha...)
(type and level of compression, BIGTIFF support, blocks size, overview, colorimetry, alpha...)
to use when outputting raster files. The parameters depend on the driver.

.. _figure_gdal_create_settings:
Expand Down
161 changes: 117 additions & 44 deletions docs/user_manual/working_with_raster/georeferencer.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,10 @@ Georeferencer
.. contents::
:local:

The |georefRun| Georeferencer is a tool for generating world files for layers.
It allows you to reference rasters or vectors to geographic or projected coordinate systems by
creating a new GeoTiff or by adding a world file to the existing image. The basic
The |georefRun| Georeferencer is a tool for aligning unreferenced raster or vector layers
to known coordinate systems using Ground Control Points (GCPs).
It supports exporting transformed rasters (GeoTIFF) and vectors (shapefiles, geopackages, etc.)
or writing accompanying world files (for raster only). The basic
approach to georeferencing a layer is to locate points on it for which
you can accurately determine coordinates.

Expand All @@ -23,36 +24,38 @@ you can accurately determine coordinates.

.. _table_georeferencer_tools:

+--------------------------------+------------------------------+-------------------------------+----------------------------+
| Icon | Purpose | Icon | Purpose |
+================================+==============================+===============================+============================+
| |addRasterLayer| | Open raster | |addOgrLayer| | Open vector |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |start| | Start georeferencing | | |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |gdalScript| | Generate GDAL Script | |loadGCPpoints| | Load GCP Points |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |saveGCPPointsAs| | Save GCP Points As | |transformSettings| | Transformation settings |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |addGCPPoint| | Add GCP Point | |deleteGCPPoint| | Delete GCP Point |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |moveGCPPoint| | Move GCP Point | |pan| | Pan |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |zoomIn| | Zoom In | |zoomOut| | Zoom Out |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |zoomToLayer| | Zoom To Layer | |zoomLast| | Zoom Last |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |zoomNext| | Zoom Next | |linkGeorefToQGis| | Link Georeferencer to QGIS |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |linkQGisToGeoref| | Link QGIS to Georeferencer | |fullHistogramStretch| | Full histogram stretch |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
| |localHistogramStretch| | Local histogram stretch | | |
+--------------------------------+------------------------------+-------------------------------+----------------------------+
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| Icon | Purpose | Icon | Purpose |
+================================+==============================+===============================+===============================+
| |addRasterLayer| | Open raster | |addOgrLayer| | Open vector |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |start| | Start georeferencing | |gdalScript| | Generate GDAL Script |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |loadGCPpoints| | Load GCP Points | |saveGCPPointsAs| | Save GCP Points As |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |transformSettings| | Transformation settings | | |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |addGCPPoint| | Add GCP Point | |deleteGCPPoint| | Delete GCP Point |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |moveGCPPoint| | Move GCP Point | |snapping| | Snapping Type |
Copy link
Collaborator

@DelazJ DelazJ Apr 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

nothing else to say on snapping?

Copy link
Collaborator

@DelazJ DelazJ Apr 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

OK, I see you just refs the issue report

+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |cad| | Show Advanced Digitizing Dock| |pan| | Pan |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |zoomIn| | Zoom In | |zoomOut| | Zoom Out |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |zoomToLayer| | Zoom To Layer | |zoomLast| | Zoom Last |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |zoomNext| | Zoom Next | |linkGeorefToQGis| | Link Georeferencer to QGIS |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |linkQGisToGeoref| | Link QGIS to Georeferencer | |fullHistogramStretch| | Full histogram stretch |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+
| |localHistogramStretch| | Local histogram stretch | | |
+--------------------------------+------------------------------+-------------------------------+-------------------------------+

Table Georeferencer: Georeferencer Tools

Usual procedure
---------------
Georeferencing raster layer
---------------------------

As X and Y coordinates (DMS (dd mm ss.ss), DD (dd.dd) or projected coordinates
(mmmm.mm)), which correspond with the selected point on the image, two
Expand Down Expand Up @@ -228,6 +231,15 @@ It is possible to choose between five different resampling methods:
#. Cubic B-Spline (4x4 kernel)
#. Lanczos (6x6 kernel)

Define the Raster creation options
Copy link
Collaborator

@DelazJ DelazJ Apr 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The raster creation options widget is available in many raster based algorithms (e.g. https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/rasteranalysis.html#advanced-parameters) and the description of that GUI is mainly at https://docs.qgis.org/testing/en/docs/user_manual/introduction/qgis_configuration.html#gdal-createoptions. So if there are details we want to add about the default profiles, I'd suggest we mention them in the config section instead, so that it benefits to all.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When exporting a raster, |checkbox| :guilabel:`Raster creation options` allows you to define
additional options that control how the output file is structured and compressed.
See more at :ref:`Raster driver options <gdal_createoptions>`.

.. tip:: Select an empty entry if you want to create your own custom combination of parameters.

Define the transformation settings
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Expand Down Expand Up @@ -258,17 +270,82 @@ raster.
* Finally, |checkbox| :guilabel:`Load in project when done` loads the output raster
automatically into the QGIS map canvas when the transformation is done.

Show and adapt raster properties
................................

Clicking on the :guilabel:`Raster properties` option in the :guilabel:`Settings`
menu opens the :ref:`Layer properties <raster_properties_dialog>` dialog of the
raster file that you want to georeference.
.. _`georeferencer_running`:

Running the transformation
..........................

After all GCPs have been collected and all transformation settings are defined,
just press the |start| :sup:`Start georeferencing` button to create
the new georeferenced raster.


Georeferencing Vector Layer
---------------------------

Georeferencing vector layers works similarly to raster georeferencing, but instead of matching image pixels,
you match vector geometries (points, lines, or polygons) to known spatial references.

The standard procedure starts the same as for raster georeferencing:
open QGIS and add a layer to the map canvas to use as a reference.
This can be a georeferenced raster or vector layer, or a WMS layer.

Open the Georeferencer dialog from :menuselection:`Layer -->` |georefRun| :menuselection:`Georeferencer`.

Start georeferencing by following these steps (in this example, we use an unreferenced ``alaska.shp``):

.. _figure_vector_georeferencer_dialog:

.. figure:: img/vector_georeferencer_dialog.png
:align: center

Vector Georeferencer Dialog

#. Load the unreferenced vector layer using the |addOgrLayer| button.
The vector layer will appear in the main working area of the dialog.

#. Activate snapping by clicking the |snapping| button and selecting the desired snapping type(s).
This enables snapping to the reference layer when placing GCPs.

You can also use the |cad| :sup:`Advanced Digitizing` dock to ensure high-precision
point selection. For more information, refer to the
:ref:`Advanced Digitizing <advanced_digitizing_panel>` section.

#. Use the |addGCPPoint| :sup:`Add GCP Point` button to add a point to the working area.
Enter its coordinates manually and set the CRS, or click the |pencil| :sup:`From map canvas` button
to pick the coordinates from a georeferenced layer in the main QGIS map canvas.
In that case, the CRS will be set automatically.

#. Define the transformation settings:

* Select the :guilabel:`Transformation type`.
The transformation algorithms are the same as those for raster georeferencing.
See :ref:`georeferencer_transformation` for more details.
* Define the :guilabel:`Target CRS` (Coordinate Reference System) for the georeferenced vector
(see :ref:`label_projections`).
* Set the output file format and path (e.g., GeoPackage, Shapefile).
By default, a new file with suffix ``_modified`` will be created in the same folder
as the original vector file.
* Optionally, enable **Generate PDF map** and **Generate PDF report**.
The report includes transformation parameters, GCP residuals, and a summary of RMS errors.
* Enable |checkbox| :guilabel:`Save GCP Points` to store GCPs in a file alongside the output vector layer.
* Enable |checkbox| :guilabel:`Load in project when done` to add the result directly to the map canvas.

#. Click |start| :sup:`Start georeferencing` to run the transformation and generate the georeferenced vector layer.

Show and adapt layer properties
--------------------------------

Clicking on the :guilabel:`Source properties` option in the :guilabel:`Settings`
menu opens the :ref:`Raster Layer properties <raster_properties_dialog>`
or :ref:`Vector Layer properties <vector_properties_dialog>` depending on the
type of layer you are georeferencing.

.. _configure_georeferencer:

Configure the georeferencer
...........................
---------------------------

You can customize the behavior of the georeferencer in :menuselection:`Settings
--> Configure Georeferencer` (or use keyboard shortcut :kbd:`Ctrl+P`).
Expand All @@ -284,14 +361,6 @@ You can customize the behavior of the georeferencer in :menuselection:`Settings
This will dock the Georeferencer window in the main QGIS window rather than
showing it as a separate window that can be minimized.

.. _`georeferencer_running`:

Running the transformation
..........................

After all GCPs have been collected and all transformation settings are defined,
just press the |start| :sup:`Start georeferencing` button to create
the new georeferenced raster.


.. Substitutions definitions - AVOID EDITING PAST THIS LINE
Expand All @@ -306,6 +375,8 @@ the new georeferenced raster.
:width: 1.5em
.. |addRasterLayer| image:: /static/common/mActionAddRasterLayer.png
:width: 1.5em
.. |cad| image:: /static/common/cad.png
:width: 1.5em
.. |checkbox| image:: /static/common/checkbox.png
:width: 1.3em
.. |deleteGCPPoint| image:: /static/common/mActionDeleteGCPPoint.png
Expand All @@ -332,6 +403,8 @@ the new georeferenced raster.
:width: 1.5em
.. |saveGCPPointsAs| image:: /static/common/mActionSaveGCPpointsAs.png
:width: 1.5em
.. |snapping| image:: /static/common/mIconSnapping.png
:width: 1.5em
.. |start| image:: /static/common/mActionStart.png
:width: 1.5em
.. |transformSettings| image:: /static/common/mActionTransformSettings.png
Expand Down
Binary file modified docs/user_manual/working_with_raster/img/transformation_settings.png
View file
Open in desktop
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
Binary file added docs/user_manual/working_with_raster/img/vector_georeferencer_dialog.png
View file
Open in desktop
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
Loading