QGIS Cloud – partial display of polygons only

QGIS Cloud: When Your Polygons Go AWOL (and How to Get Them Back)

So, you’re using QGIS Cloud, right? Awesome! It’s a super handy way to get your QGIS maps online without wrestling with servers and all that jazz. Think of it as your own little spatial data infrastructure (SDI), minus the headache i. You can whip up maps, manage your data, and share it all with the world i. But sometimes… things go sideways. Ever uploaded a map only to find your polygon layers are looking a little… sparse? Like they’ve got geographical Swiss cheese holes all over them? Yeah, it’s frustrating. Let’s dive into why this happens and, more importantly, how to fix it.

The Usual Suspects: Why Your Polygons Are Playing Hide-and-Seek

Honestly, nine times out of ten, it boils down to your data. Think of it like this: if your source data is wonky, your map’s gonna be wonky too i. Corrupted shapefiles are a classic culprit. You might not even notice the errors in QGIS desktop, but QGIS Cloud? It’ll find ’em. Trust me.

But it’s not always corruption. Sometimes, it’s just plain bad geometry. Self-intersections, overlapping polygons, unclosed shapes – these are all geometry gremlins that can mess with your rendering i. It’s like trying to build a house on a shaky foundation; things are gonna crumble.

Then there’s the whole Coordinate Reference System (CRS) thing. If your data’s in one CRS and your project’s in another, you’re asking for trouble i. Imagine trying to fit a square peg in a round hole – you’ll get distortions and incomplete rendering, especially when you’re dealing with areas near the poles.

And let’s not forget about size. QGIS Cloud’s free version is pretty generous, but it’s not unlimited. You get 50 MB for your database i. If your polygon layers are massive, with tons of vertices, you might be pushing the limits. It’s like trying to cram too much luggage into an overhead bin – something’s gotta give. Plus, the free version has some limitations, such as SSL support and personalization i.

Finally, sometimes it’s the rendering settings themselves. Tweaks you made in QGIS Desktop, if not done right, can cause problems when you upload to QGIS Cloud. Simplification settings, for example, can sometimes create gaps where you don’t want them i.

Become a Polygon Detective: Troubleshooting Time!

Alright, enough doom and gloom. Let’s get practical. Here’s how to hunt down those missing polygons and bring them back into the fold:

Bonus Round: Point Clouds

Okay, we’ve been talking about polygons, but what about point clouds? They can have similar display issues, especially because they tend to be massive. If you’re dealing with point clouds, consider these tips:

• COPC is Your Friend: Convert your point clouds to Cloud Optimized Point Cloud (COPC) format i. It’s designed for efficient streaming and rendering.
• Thin It Out: Reduce the density of your point cloud using thinning algorithms i. You don’t need every single point to get the picture.
  • Clip It Good: Clip your point cloud to the area you’re interested in using a polygon layer i. Why render data you don’t need?

The Bottom Line

Polygon problems in QGIS Cloud can be a pain, but they’re usually fixable. By systematically checking your data, tweaking your settings, and maybe even upgrading to Pro, you can get those polygons back where they belong: on your map, looking beautiful. Happy mapping!