.. only:: html
.. index:: Raster, Layer properties
.. _raster_properties_dialog:
************************
Raster Properties Dialog
************************
.. only:: html
.. contents::
:local:
To view and set the properties for a raster layer, double click on the layer name
in the map legend, or right click on the layer name and choose :guilabel:`Properties`
from the context menu. This will open the :guilabel:`Raster Layer Properties` dialog.
There are several tabs in the dialog:
* |metadata| :ref:`Information `
* |system| :ref:`Source `
* |symbology| :ref:`Symbology `
* |transparency| :ref:`Transparency `
* |rasterHistogram| :ref:`Histogram `
* |rendering| :ref:`Rendering `
* |pyramids| :ref:`Pyramids `
* |editMetadata| :ref:`Metadata `
* |legend| :ref:`Legend `
* |overlay| :ref:`QGIS Server `
.. tip:: **Live update rendering**
The :ref:`layer_styling_panel` provides you with some of the common features
of the Layer properties dialog and is a good modeless widget that
you can use to speed up the configuration of the layer styles and
automatically view your changes in the map canvas.
.. note::
Because properties (symbology, label, actions, default values, forms...) of
embedded layers (see :ref:`nesting_projects`) are pulled from the original
project file and to avoid changes that may break this behavior, the layer
properties dialog is made unavailable for these layers.
.. _raster_information:
Information Properties
======================
The |metadata| :guilabel:`Information` tab is read-only and represents an interesting
place to quickly grab summarized information and metadata on the current layer.
Provided information are:
* based on the provider of the layer (format of storage, path, data type, extent,
width/height, compression, pixel size, statistics on bands, number of columns,
rows and no-data values of the raster...);
* picked from the :ref:`filled metadata `: access, links,
contacts, history... as well as data information (CRS, Extent, bands...).
.. _label_sourcetab:
Source Properties
=================
The |system| :guilabel:`Source` tab displays basic information about the selected
raster, including:
* the :guilabel:`Layer name` to display in the :guilabel:`Layers Panel`;
* setting the :guilabel:`Coordinate Reference System`:
Displays the layer's Coordinate Reference System (CRS) as a PROJ.4 string. You
can change the layer's CRS, selecting a recently used one in the drop-down list
or clicking on |setProjection| :sup:`Select CRS` button (see :ref:`crs_selector`).
Use this process only if the CRS applied to the layer is a wrong one or if none
was applied. If you wish to reproject your data into another CRS, rather use
layer reprojection algorithms from Processing or :ref:`Save it into another
layer `.
.. _figure_raster_properties:
.. figure:: img/rasterPropertiesDialog.png
:align: center
Raster Layers - Source Properties Dialog
.. index:: Symbology, Single Band Raster, Three Band Color Raster, Multi Band Raster
.. _label_symbology:
Symbology Properties
====================
Band rendering
--------------
QGIS offers four different :guilabel:`Render types`.
The renderer chosen is dependent on the data type.
#. :ref:`Multiband color ` - if the file comes as a multiband with
several bands (e.g., used with a satellite image with several bands).
#. :ref:`Paletted/Unique values ` - for single band files that come with an
indexed palette (e.g., used with a digital topographic map) or for general use of
palettes for rendering raster layers.
#. :ref:`Singleband gray ` - (one band of) the image will be rendered
as gray; QGIS will choose this renderer if the file has neither multibands nor an
indexed palette nor a continuous palette (e.g., used with a shaded relief map).
#. :ref:`Singleband pseudocolor ` - this renderer is possible for
files with a continuous palette, or color map (e.g., used with an elevation map).
#. :ref:`Hillshade ` - Creates hillshade from a band.
.. _multiband_color:
Multiband color
...............
With the multiband color renderer, three selected bands from the image will be
rendered, each band representing the red, green or blue component that will be
used to create a color image. QGIS automatically fetches
:guilabel:`Min` and :guilabel:`Max` values for each band of the raster and scales
the coloring accordingly. You can control the value ranges with the help
of the :ref:`Min/Max Value Settings ` section.
A :guilabel:`Contrast enhancement` method can also be applied to the values:
'No enhancement', 'Stretch to MinMax', 'Stretch and clip to MinMax' and 'Clip to min max'.
.. index:: Contrast enhancement
.. note:: **Contrast enhancement**
When adding GRASS rasters, the option *Contrast enhancement* will always be
set automatically to *stretch to min max*, regardless of if this is set to
another value in the QGIS general options.
.. _figure_raster_multiband:
.. figure:: img/rasterMultibandColor.png
:align: center
Raster Symbology - Multiband color rendering
.. tip:: **Viewing a Single Band of a Multiband Raster**
If you want to view a single band of a multiband
image (for example, Red), you might think you would set the Green and Blue
bands to :guilabel:`Not Set`. But this is not the correct way. To display the Red band,
set the image type to :ref:`Singleband gray `, then select Red
as the :guilabel:`Gray band` to use.
.. _paletted:
Paletted/Unique values
......................
This is the standard render option for singleband files that include
a color table, where a certain color is assigned to each pixel value.
In that case, the palette is rendered automatically.
It can be used for all kinds of raster bands, assigning a
color to each unique raster value.
If you want to change a color, just double-click on the color and
the :guilabel:`Select color` dialog appears.
It is also possible to assign labels to the colors.
The label will then appear in the legend of the raster layer.
Right-clicking over selected rows in the color table shows a
contextual menu to:
* :guilabel:`Change Color...` for the selection
* :guilabel:`Change Opacity...` for the selection
* :guilabel:`Change Label...` for the selection
.. _figure_raster_paletted_unique:
.. figure:: img/rasterPalettedUniqueValue.png
:align: center
Raster Symbology - Paletted unique value rendering
The pulldown menu, that opens when clicking the :guilabel:`...`
(:guilabel:`Advanced options`) button below the color map to the
right, offers color map loading
(:guilabel:`Load Color Map from File...`) and exporting
(:guilabel:`Export Color Map to File...`), and loading of classes
(:guilabel:`Load Classes from Layer`).
.. _singleband_gray:
Singleband gray
...............
This renderer allows you to render a single band layer with a :guilabel:`Color
gradient`: 'Black to white' or 'White to black'. You can define a range of values
to color other than the default :guilabel:`Min` and :guilabel:`Max` values of the
whole raster, thanks to the :ref:`Min/Max Value Settings ` option.
Again, a :guilabel:`Contrast enhancement` method can be applied to the values:
'No enhancement', 'Stretch to MinMax', 'Stretch and clip to MinMax' and 'Clip to min max'.
.. _figure_raster_gray:
.. figure:: img/rasterSingleBandGray.png
:align: center
Raster Symbology - Singleband gray rendering
.. index:: Color map, Color interpolation, Discrete
.. _label_colormaptab:
Singleband pseudocolor
......................
This is a render option for single-band files that include a
continuous palette.
You can also create color maps for a bands of a multiband raster.
.. _figure_raster_pseudocolor:
.. figure:: img/rasterSingleBandPseudocolor.png
:align: center
Raster Symbology - Singleband pseudocolor rendering
Using a :guilabel:`Band` of the layer and a :ref:`values range `,
three types of color :guilabel:`Interpolation` are available:
* Discrete (a <= symbol appears in the value column)
* Linear
* Exact (an equal symbol appears in the Value column)
The :guilabel:`Color ramp` drop down list lists the color ramp in your QGIS. You
can add a new one, edit or save the one you changed. The name of the color ramp
will be saved in the configuration and in the QML files.
The :guilabel:`Label unit suffix` is a label added after the value in the
legend.
For the classification :guilabel:`Mode` |selectString| 'Equal interval', you
only need to select the :guilabel:`number of classes` |selectNumber| and press
the button :guilabel:`Classify`.
In the case of the :guilabel:`Mode` |selectString| 'Continuous', QGIS creates
classes automatically depending on the :guilabel:`Min` and :guilabel:`Max`.
The button |signPlus| :sup:`Add values manually` adds a value
to the individual color table. The button |signMinus| :sup:`Remove selected row`
deletes a value from the individual color table. Double clicking on the value column
lets you insert a specific value. Double clicking on the color column opens the dialog
:guilabel:`Change color`, where you can select a color to apply on that value.
Further, you can also add labels for each color, but this value won't be displayed
when you use the identify feature tool.
Right-clicking over selected rows in the color table shows a
contextual menu to:
* :guilabel:`Change Color...` for the selection
* :guilabel:`Change Opacity...` for the selection
You can use the buttons |fileOpen| :sup:`Load color map from file`
or |fileSaveAs| :sup:`Export color map to file` to load an existing
color table or to save the color table for later use.
The |checkbox| :guilabel:`Clip out of range values` allows QGIS to not render pixel
greater than the :guilabel:`Max` value.
.. index:: Hillshade
.. _hillshade_renderer:
Hillshade
.........
Render a band of the raster layer using hillshading.
.. _figure_raster_hillshade:
.. figure:: img/rasterHillshade.png
:align: center
Raster Symbology - Hillshade rendering
Options:
* :guilabel:`Band`: The raster band to use.
* :guilabel:`Altitude`: The elevation angle of the light source (default is ``45°``).
* :guilabel:`Azimuth`: The azimuth of the light source (default is ``315°``).
* :guilabel:`Z Factor`: Scaling factor for the values of the raster band (default is ``1``).
* |checkbox| :guilabel:`Multidirectional`: Specify if multidirectional hillshading
is to be used (default is ``off``).
.. _minmaxvalues:
Setting the min and max values
..............................
By default, QGIS reports the :guilabel:`Min` and :guilabel:`Max` values of the band(s)
of the raster. A few very low and/or high values can have a
negative impact on the rendering of the raster. The :ref:`Min/Max Value Settings
` menu helps you control the values to render.
.. _figure_raster_minmaxvalues:
.. figure:: img/rasterMinMaxValues.png
:align: center
Raster Symbology - Min and Max Value Settings
Available options are:
* |radioButtonOff| :guilabel:`User defined`: The default
:guilabel:`Min` and :guilabel:`Max` values of the band(s) can be overridden
* |radioButtonOff| :guilabel:`Cumulative count cut`: Removes outliers.
The standard range of values is ``2%`` to ``98%``, but can
be adapted manually.
* |radioButtonOn| :guilabel:`Min/max`: Uses the whole range of values in the image band.
* |radioButtonOff| :guilabel:`Mean +/- standard deviation x`: Creates a color
table that only considers values within the standard deviation or within multiple
standard deviations. This is useful when you have one or two cells with abnormally
high values in a raster grid that are having a negative impact on the rendering
of the raster.
Calculations of the min and max values of the bands are made based on the:
* :guilabel:`Statistics extent`: it can be :guilabel:`Whole raster`,
:guilabel:`Current canvas` or :guilabel:`Updated canvas`.
:guilabel:`Updated canvas` means that min/max values used for the
rendering will change with the canvas extent (dynamic stretching).
* :guilabel:`Accuracy`, which can be either
:guilabel:`Estimate (faster)` or :guilabel:`Actual (slower)`.
.. note:: For some settings, you may need to press the :guilabel:`Apply` button of
the layer properties dialog in order to display the actual min and max values
in the widgets.
Color rendering
---------------
For every :guilabel:`Band rendering`, a :guilabel:`Color rendering` is possible.
You can also achieve special rendering effects for your raster file(s) using one
of the blending modes (see :ref:`blend-modes`).
Further settings can be made in modifying the :guilabel:`Brightness`, the
:guilabel:`Saturation` and the :guilabel:`Contrast`. You can also use a :guilabel:`Grayscale`
option, where you can choose between 'By lightness', 'By luminosity' and 'By average'.
For one hue in the color table, you can modify the 'Strength'.
Resampling
----------
The :guilabel:`Resampling` option makes its appearance when you zoom in and out of an
image. Resampling modes can optimize the appearance of the map. They calculate a new gray value
matrix through a geometric transformation.
.. _figure_raster_resampling:
.. figure:: img/rasterRenderAndRessampling.png
:align: center
Raster Symbology - Color rendering and Resampling settings
When applying the 'Nearest neighbour' method, the map can have a pixelated
structure when zooming in. This appearance can be improved by using the
'Bilinear' or 'Cubic' method, which cause sharp features to be blurred.
The effect is a smoother image. This method can be applied, for instance,
to digital topographic raster maps.
At the bottom of the :guilabel:`Symbology` tab, you can see a thumbnail of the layer,
its legend symbol, and the palette.
.. index:: Transparency
.. _raster_transparency:
Transparency Properties
=======================
|transparency| QGIS has the ability to display each raster layer at a different transparency level.
Use the transparency slider |slider| to indicate to what extent the underlying layers
(if any) should be visible through the current raster layer. This is very useful
if you like to overlay more than one raster layer (e.g., a shaded relief map
overlayed by a classified raster map). This will make the look of the map more
three dimensional.
.. _figure_raster_transparency:
.. figure:: img/rasterTransparency.png
:align: center
Raster Transparency
Additionally, you can enter a raster value that should be treated as *NODATA* in
the :guilabel:`Additional no data value` option.
An even more flexible way to customize the transparency can be done in the
:guilabel:`Custom transparency options` section:
* Use :guilabel:`Transparency band` to apply transparency on an entire band.
* Provide a list of pixels to make transparent with the corresponding level of
transparency:
#. Click the |signPlus| :sup:`Add values manually` button. A new row will
appear in the pixel list.
#. Enter the **Red**, **Green** and **Blue** values of the pixel and adjust
the **Percent Transparent** to apply.
#. Alternatively, you can directly fetch the pixel values directly from the
raster using the |contextHelp| :sup:`Add values from display` button.
Then enter the transparency value.
#. Repeat the steps to adjust more values with custom transparency.
#. Press the :guilabel:`Apply` button and have a look at the map.
As you can see, it is quite easy to set custom transparency, but it can be
quite a lot of work. Therefore, you can use the button |fileSave|
:sup:`Export to file` to save your transparency list to a file. The button
|fileOpen| :sup:`Import from file` loads your transparency settings and
applies them to the current raster layer.
.. index:: Histogram
.. _label_histogram:
Histogram Properties
====================
The |rasterHistogram| :guilabel:`Histogram` tab allows you to view the distribution
of the bands or colors in your raster. The histogram is generated when you press the
:guilabel:`Compute Histogram` button. All existing bands will be displayed together.
You can save the histogram as an image with the |fileSave| button.
At the bottom of the histogram, you can select a raster band in the drop-down
menu and :guilabel:`Set min/max style for` it.
The |actionRun| :guilabel:`Prefs/Actions` drop-down menu gives you advanced
options to customize the histogram:
* With the :guilabel:`Visibility` option, you can display histograms of the individual
bands. You will need to select the option |radioButtonOff| :guilabel:`Show selected
band`.
* The :guilabel:`Min/max options` allow you to 'Always show min/max markers', to 'Zoom
to min/max' and to 'Update style to min/max'.
* The :guilabel:`Actions` option allows you to 'Reset' or 'Recompute histogram' after
you changed the min or max values of the band(s).
.. _figure_raster_histogram:
.. figure:: img/rasterHistogram.png
:align: center
Raster Histogram
.. index:: Rendering
.. _raster_rendering:
Rendering Properties
====================
In the |rendering| :guilabel:`Rendering` tab, it's possible to:
* apply a :guilabel:`Scale dependent visibility` to the layer:
You can set the :guilabel:`Maximum (inclusive)` and :guilabel:`Minimum
(exclusive)` scale, defining a range of scale in which the layer will be
visible. Out of this range, it's hidden. The |mapIdentification|
:sup:`Set to current canvas scale` button helps you use the current map
canvas scale as boundary of the range visibility.
See :ref:`label_scaledepend` for more information.
* :guilabel:`Refresh layer at interval (seconds)`: set a timer to automatically
refresh individual layers at a matching interval. Canvas updates are
deferred in order to avoid refreshing multiple times if more than one layer
has an auto update interval set.
You can set the :guilabel:`Maximum (inclusive)` and :guilabel:`Minimum
(exclusive)` scale, defining a range of scale in which the layer will be
visible. Out of this range, it's hidden. The |mapIdentification|
:sup:`Set to current canvas scale` button helps you use the current map
canvas scale as boundary of the range visibility.
See :ref:`label_scaledepend` for more information.
.. _figure_raster_rendering:
.. figure:: img/rasterRendering.png
:align: center
Raster Rendering
.. index:: Pyramids
.. _raster_pyramids:
Pyramids Properties
===================
Large resolution raster layers can slow navigation in QGIS. By creating lower
resolution copies of the data (pyramids), performance can be considerably
improved, as QGIS selects the most suitable resolution to use depending on the
level of zoom.
You must have write access in the directory where the original data is stored
to build pyramids.
From the :guilabel:`Resolutions` list, select resolutions for which you want to
create pyramid by clicking on them.
If you choose **Internal (if possible)** from the :guilabel:`Overview format`
drop-down menu, QGIS tries to build pyramids internally.
.. note::
Please note that building pyramids may alter the original data file, and once
created they cannot be removed. If you wish to preserve a 'non-pyramided'
version of your raster, make a backup copy prior to building pyramids.
If you choose **External** and **External (Erdas Imagine)** the pyramids will
be created in a file next to the original raster with the same name and a
:file:`.ovr` extension.
Several :guilabel:`Resampling methods` can be used to calculate the pyramids:
* Nearest Neighbour
* Average
* Gauss
* Cubic
* Cubic Spline
* Laczos
* Mode
* None
Finally, click :guilabel:`Build Pyramids` to start the process.
.. _figure_raster_pyramids:
.. figure:: img/rasterPyramids.png
:align: center
Raster Pyramids
.. index:: Metadata, Metadata editor, Keyword
.. _raster_metadata:
Metadata Properties
===================
The |editMetadata| :guilabel:`Metadata` tab provides you with options to create
and edit a metadata report on your layer. See :ref:`vector layer metadata
properties ` for more information.
.. index:: Legend, Embedded widget
.. _raster_legend:
Legend Properties
=================
The |legend| :guilabel:`Legend` tab provides you with a list of widgets you can
embed within the layer tree in the Layers panel. The idea is to have a way to
quickly access some actions that are often used with the layer (setup
transparency, filtering, selection, style or other stuff...).
By default, QGIS provides transparency widget but this can be extended by
plugins registering their own widgets and assign custom actions to layers
they manage.
.. index:: QGIS Server
.. _raster_server:
QGIS Server Properties
======================
The |overlay| :guilabel:`QGIS Server` tab displays a wealth of information about
the raster layer, including statistics about each band in the current raster layer.
From this tab, entries may be made for the :guilabel:`Description`,
:guilabel:`Attribution`, :guilabel:`MetadataUrl` and :guilabel:`Properties`.
In :guilabel:`Properties`, statistics are gathered on a 'need to know'
basis, so it may well be that a given layer's statistics have not yet been
collected.
.. _figure_raster_metadata:
.. figure:: img/rasterMetadata.png
:align: center
QGIS Server in Raster Properties
.. Substitutions definitions - AVOID EDITING PAST THIS LINE
This will be automatically updated by the find_set_subst.py script.
If you need to create a new substitution manually,
please add it also to the substitutions.txt file in the
source folder.
.. |actionRun| image:: /static/common/mAction.png
:width: 1.5em
.. |checkbox| image:: /static/common/checkbox.png
:width: 1.3em
.. |contextHelp| image:: /static/common/mActionContextHelp.png
:width: 1.5em
.. |editMetadata| image:: /static/common/editmetadata.png
:width: 1.2em
.. |fileOpen| image:: /static/common/mActionFileOpen.png
:width: 1.5em
.. |fileSave| image:: /static/common/mActionFileSave.png
:width: 1.5em
.. |fileSaveAs| image:: /static/common/mActionFileSaveAs.png
:width: 1.5em
.. |legend| image:: /static/common/legend.png
:width: 1.2em
.. |mapIdentification| image:: /static/common/mActionMapIdentification.png
:width: 1.5em
.. |metadata| image:: /static/common/metadata.png
:width: 1.5em
.. |overlay| image:: /static/common/overlay.png
:width: 1.5em
.. |pyramids| image:: /static/common/pyramids.png
:width: 1.5em
.. |radioButtonOff| image:: /static/common/radiobuttonoff.png
:width: 1.5em
.. |radioButtonOn| image:: /static/common/radiobuttonon.png
:width: 1.5em
.. |rasterHistogram| image:: /static/common/rasterHistogram.png
:width: 1.5em
.. |rendering| image:: /static/common/rendering.png
:width: 1.5em
.. |selectNumber| image:: /static/common/selectnumber.png
:width: 2.8em
.. |selectString| image:: /static/common/selectstring.png
:width: 2.5em
.. |setProjection| image:: /static/common/mActionSetProjection.png
:width: 1.5em
.. |signMinus| image:: /static/common/symbologyRemove.png
:width: 1.5em
.. |signPlus| image:: /static/common/symbologyAdd.png
:width: 1.5em
.. |slider| image:: /static/common/slider.png
.. |symbology| image:: /static/common/symbology.png
:width: 2em
.. |system| image:: /static/common/system.png
:width: 1.5em
.. |transparency| image:: /static/common/transparency.png
:width: 1.5em