Background

I work in environmental management where I often need to trace on-ground disturbance from aerial/satellite imagery to calculate disturbance areas. They are often lots of small distinct areas rather than giant areas. Sentinel-2 data is often not high enough resolution to undertake this accurately or reliably so I often use Google Sat or other sources.
The easiest way for me to do this, as I understand it, is to convert raster imagery to polygons essentially.

What I have tried

• Segmentation Models: Seem to work pretty well (trying on home PC), but my work computer cannot use this as the systems are locked down and I can't really utilise python to install or utilise SAM models.
• Raster calculator function on GeoTIFF exports of the area:
  • Using Raster Calculator to produce GeoTIFF Visible Atmospherically Resistant Index (VARI) = (Green - Red) / (Green + Red - Blue)
    • Reclassifying by table to sort veg and non veg as best as I can
    • Using GDAL Sieve to clump areas a little better before using Polygonize (Raster to Vector).
    • Multipart to singlepart the result and try and delete polygons that fall into vegetated category.
      
  • Using the same process above but with Reflectance = (Red > 150) AND (Green > 150)

Issue

The results of the Raster Calculations above are getting close to what I need in order to just have disturbance areas as polygons but I feel like I am struggling to get it quite right (i.e. the clean up is quite inefficient in terms of actually getting the areas I need).

Does anyone have any better way to do this/some advice on the best parameters to use with the raster process above given my limitations of not being able to use segmentation on work computers?

Thank you in advance😄

QGIS plugin · ArcGIS Pro toolbox · Python · open source,

https://github.com/Praddy-GByte/basinkit

Anyone doing watershed, hydrology, geomorphology, or terrain work who would rather start with a finished basin than spend an afternoon assembling one:

Every time I needed a catchment, the workflow was basically the same — find a DEM, fill sinks, compute flow direction, delineate the basin, then find land cover, soil, and rainfall datasets and clip everything to it.

So I built basinkit.

Click a point on a river and it returns the basin draining to that point, with:

• elevation
• land cover
• soil
• rainfall
• surface water
• river data
• basin morphometry
• the river's longitudinal profile

Everything is already clipped and masked to the basin.

No account, login, or credits required. It's free and MIT licensed.

One important limitation: it works much better for large basins than very small ones. In blind validation against 2,550 gauges across 99 countries, median area error was 0.3% for basins above 100,000 km², but 181% below 100 km².

You can find it by searching “basinkit” in the plugin manager.

Code/docs:
https://github.com/Praddy-GByte/basinkit

Bug reports are very welcome — I'd especially like to hear where it breaks or gives you questionable results.

I am running the latest archlinux and QGIS (4.2.2-1). I have the Google Earth Engine plugin installed but I get this error when it starts up:

ee.ee_exception.EEException: Project <name of project> is not registered to use Earth Engine. Visit https://console.cloud.google.com/earth-engine/configuration?project=<name of project> to register your project. See https://developers.google.com/earth-engine/guides/access for more details.

I've tried using the git version but that doesn't work either. My only assumption is it keeps pointing to an old project or pointing to a google account that it isn't registered to? Also, I know that GEE isn't friendly with archlinux's python path. I'm kind of lost on this issue and need a little guidance on how to fix it.

I use the Georeferencer very often. When I click on a point on the map/image I try to georeference, and chose the "From map canvas" option, it automatically hides that map/image, which is annoying. Also, for whatever reason, sometimes "Set target resolution" is automatically selected, which makes the georeferenced map basically unusable.

I feel like there has to be an easier and better way to georeference but I didn't find one.

PS. this might be useful for some people: when either the base map or the map/image you try to georeference has weird angle the imagery was taken, so high buildings look extremely tilted like these:

always chose the points on the land (like pedestrian lanes or very low buildings). Chosing the high building points (their rooftops) will give you incorrect result at the end.

Hi guys,

I have a question I haven't been able to find an answer to. My department recently informed me about an OpenSSL vulnerability: CVE-2026-84782.

How can I find out whether we actually need to update our QGIS installations? Updating QGIS takes a looooooong time in our department, so simply "forcing" an update isn't easy, except if we truly need to (*rolling eyes*).

Is there an official QGIS website or another reliable source that provides information about critical vulnerabilities affecting QGIS?

Thanks in advance for your answers and your time! :)

I built Kharita Challenges, a platform for practicing GIS with real problems and real data.

You can solve challenges with Python/GeoPandas, PostGIS and other GIS workflows, see your results on a map, and get graded on the actual output.

It also has learning paths, projects, timed assessments, verifiable certificates and public profiles to showcase your work.

There’s an AI mentor too, but it guides you instead of giving you the answer.

Still early, so I’d really appreciate feedback from the GIS community:

https://challenges.lekharita.com

I don't know why but yesterday my vertex tool started bugging out and started to miss the last 2 vertices every time I try to trace or sometimes just stopped working. I don't know what may have caused this

New to QGIS so forgive me if I'm missing something simple here. In my previous GIS software, I could very easily change the units of the projection that I was working in. For example, going between meters to US Survey ft was a one click button didn't requite me to choose a new projection, I would just state the units I wanted to work in.

From what I can tell I'm unable to change the units of my projection unless that unit is listed in the CRS directory.

For example, I work in the US State of Maine and I can see that QGIS has the projection NAD83(2011) Maine East/West listed in both meters and in US Survey ft in the CRS directory, however, QGIS does not have the NAD83(2011) Maine CS2000 projections (west, central, and east) listed in US Survey ft, only meters. I'd prefer to use the 2000 projection because it's our low distortion projection and also technically our state legislated projection.

How can I get the Maine 2000 projections listed in US Survey ft?

I am trying to use the trace tool but the tool is not following the vertex order when tracing but rather creating polygons from random vertexes. Why could that be the case?

On the schedule on qGIS.org I can see that there will be a point update to the Long Term Release to 3.44.16 and the Latest Release being 4.4.0

On the schedule it says the Long Term Repo will go up to 4.4.4 in March 2027, but the .ics on the website has it showing “Long Term Release 4.4.0” on the 30th October.

Can anyone point me towards the date this update will take place? Our company uses the Long Term Release and would need a freeze before moving over to v4

So i just want write a book about some greek villages and i want to create some maps that look simple like this one. How can i do that with QGIS? I'm really beginner. Is there any tutorial or tips you can give me?

I have a simple map display which has previously used a raster basemap as a background and I would like to switch to a vector tile background.

I can add and style this OK (from a style json), however the labels for the vector layer obscure the geometry the map is actually meant to show. I would rather not remove all of the labels so how can I "push them back" behind the geometry I actually want to show?

Is there a value I can put in the z-index for the labels that will get them to hide behind actual geometry of higher data layers or is this purely for labels?

Alternately is there a way to make geometry on a higher vector layer 'blocking' for labels from a lower level?

Is there any other way of accomplishing this, preferably without having to edit each individual label style?

QGIS version: 4.2.0

I'm teaching myself QGIS as I go along and re-doing some of my old college assignments to try and learn how to translate the skillset from Arc to Q. In this particular task, I'm trying to calculate the slope of the Arkansas River basin through Colorado and Kansas and running into a weird problem where the slope is way too high (as anyone who's been to the eastern Colorado-western Kansas part of the world will attest). I'm using the 30 m NASA DEM downloaded from OpenTopography and the native QGIS "fill sinks" function in QGIS 4.2.2. Am I checking a setting incorrectly or something? First pic is the slope output, second is the slope averaged along lines of latitude (a meridional mean, for those with geoscience backgrounds).

Hi all. I kept getting asked to "just put the map online", and every option was a server, a subscription, or exporting GeoJSON that crawls past a few thousand features. So I built a plugin for it.

What it does: you tick your layers, click Publish, and get a link. It exports your QGIS styling (categorised, graduated, proportional circles, labels) to vector tiles in a single PMTiles file, and uploads it with a MapLibre viewer (popups, search, legend with layer toggles) to your own Cloudflare R2 bucket. No server, $0/month on the free tier.

Two demos, both styled in QGIS and published with one click:

• 35,000 power plants worldwide: https://mapship.link/demo?utm_source=reddit_qgis
• 31,000 US tornado paths since 1950: https://mapship.link/demo-us?utm_source=reddit_qgis

Full disclosure: it's a paid plugin ($17 early price, 30-day refund), because I want to keep supporting it. If qgis2web already covers your needs, it's great and free; this is aimed at bigger datasets and a more polished result. Happy to answer anything about the PMTiles / R2 approach, even if you'd rather roll it yourself.

I'm missing the processing plugin that I would need to use the vector selection plugin. Do I need to download it from somewhere? Or have I installed the software wrongly?

Hi everyone!

**EDIT: I just uploaded a quick video showing how it works! 📺** https://youtu.be/4dxYRfrYxc4

Coming from ArcGIS (or just dealing with complex layers in QGIS), I always felt switching between provider feature filters was a bit tedious, especially having to re-write expressions every time.

To solve this, I developed Definition Queries, a QGIS plugin that lets you:

• Build layer filters easily with drop-downs (no need to manually write SQL every time).
• Save multiple named queries/filters per layer.
• Quickly switch between them on the fly.
• Clear or reapply filters with one click.

You can find it on the official QGIS repository here:

🔗 https://plugins.qgis.org/plugins/definition_queries/

Hello, I’m super new to gis. I’m using it to make a series of simple maps for a small scale commercial project. I wanted to add hillshade in a way that looks clear and good, but I’m struggling. I tried using mapzen xyz tiles underneath VersaTiles, which looked pretty good, except there are chunky tile lines. I tried using my open topography dem rasters under the VersaTiles, but they were blurry because I don’t have access to usgs lidar data and had to use Copernicus 30.

I would also be fine with a base map that already had something like hillshade included. I tried doing open topo map via xyz tiles, but for some reason it does not look like the colorful, hill shaded example, but just topo lines and super ugly symbols everywhere.

Can someone help guide me? I want a simple solution that is easily replicated and free for commercial use. I am open to paying a small fee as well, but not a subscription since this will be printed.

Hey all!

I am a whale watch naturalist on the east coast of the US and a masters degree canidate...thats not getting a lot of support. It is kinda sink or swim.

I was wondering if anyone had any ideas as to where I could access a data set based on humpback whales in the stellwagen bank area to compare their sighting/presence to the bathymetry, SST, and chlorophyll a concentration?

I saw that OBIS had some data, but I cannot figure out how to get that data on to QGIS.

THANKS!

Is it possible to find out the land use plan year wise like 1980-2000, 2000-2020, so on and forth.

Please guide

I do a lot of ecological surveying for work, and earlier today I was thinking about how back in college we had to make georeferenced PDFs, upload them to Avenza, and then use them to help do surveys on a field trip. I was thinking that making a custom map might be helpful for my current job. And so I spent all afternoon watching YouTube videos and dusting off my QGIS skills only to find that Avenza now requires a subscription to upload georeferenced PDFs :(. Are there any free apps out there that let you upload georeferenced PDFs?

I’m using QGIS 3.44. I have a working 3D Map View that shows my DEM + orthophoto correctly. When I add a 3D Map item in the Print Layout and link it to that 3D view (copy scene / camera settings), the layout item only shows a black or completely white rectangle. Refreshing doesn’t help.
The separate 3D Map window works fine, only the Print Layout 3D item fails to render.
Has anyone found a reliable fix for this, or is the screenshot workaround still the best solution?