Raster VAT table support in QGIS
Crowdfunding Status: Ongoing
Funding Goal: R75000 / ~$4700 USD
Funds Raised: -
Target date: 30 November 2020
What we will build
Raster layers are better with legends! There is a ticket in the QGIS issue tracker that already describes this requirement well (see https://github.com/qgis/QGIS/issues/22427) so we will quote from there:
Many categorical raster datasets, such as those representing vegetation and landcover, have associated attribute tables. There are the usual value and count columns, but there are also often additional fields that hold useful vegetation descriptions. These might include vegetation type, vegetation complex, landcover type etc. ERDAS Imagine raster files will have a .vat.dbf with these attributes.
It would be incredibly useful to be able to open this attribute table as you can with a vector dataset. Then queries could be run and the corresponding cells highlighted. Additional columns could be added, and used to classify cells into new categories without having to do an r.recode or similar operation. For instance, you could assign weights this way, to prepare for site selection model. Additionally, these attribute columns could be made available to style the raster via the Categorized or Rule based renderers. For example, a vegetation dataset could be brought in and styled by the vegetation type attribute column. Or groups of vegetation/landcover types could be given a color with the Rule based renderer. - Credit for original text, Kurt Menke
We would like to add this feature for you! Here are some screencasts showing how it will work:
NB: We have factored in two years of maintenance and support for this feature, which accounts for about half the cost but will ensure that we take on the responsibility of fixing bugs, handling version changes etc. This way, you can trust that the feature will become a stable, sustainable part of QGIS.
If we get more than the funding goal, we will work on the following stretch goals:
- Allow QGIS to save the raster legend to a VAT table for interoperability with other software
- Enable QGIS Identify feature info tool to read feature info from Raster VAT Table
- Let us know what other related features you would like
How to fund
If we reach or exceed the target by the target date we'll invoice you and start (or continue) development. As soon as all or part of the work is completed it will be released in a nightly build of QGIS and ultimately in the next release.
You can pledge in these currencies: USD, EUR, CAN, AUD, GBP or ZAR. If you would like to pledge in another currency please enquire.
If you are based in South Africa and pledging in ZAR, please take VAT into account as we will have to charge 15% VAT.
Samweli Mwakisambwe, one of Kartoza's core QGIS committers, will work on this feature. He contributed core elements of the QGIS temporal framework and core WMS-T support to QGIS 3.14 in early 2020 with funding from the Meterological Service of Canada, through a Kartoza contract with MapGears.
Tim Sutton has been a core QGIS committer since 2001, is an honorary QGIS PSC member and has been the QGIS PSC Chair.
Other Kartoza staff have made various QGIS core contributions and written various QGIS Python plugins.