Hello, unfortunately I can’t find anything on the internet to automatically repair these errors in the mesh.
Can anyone help me with this?
Thanks a lot
This mesh is… a mess 
I would suggest retopologizing, using the Remesh modifier or another retopologizer
Hi Martin,
Have you considered trying https://www.blendermarket.com/products/instantclean [$]. I’ve picked it up on sale recently but haven’t tried it myself yet but it might help. If you share the mesh I could try it, if you want. As Joseph suggested though retopologizing might be the answer or refining your technique for generating/building your mesh.
Cheers,
Paul
many thanks for the many answers and suggestions 
Unfortunately, the bottom side looks even worse. I had thought about a “convert grid to highmap to grid”, but then unfortunately the overhangs are missing. Is there somehow a kind of “vacuum deep drawing” (see picture) only with a grid.
@moonboots :I was also looking for such a tool… but unfortunately it does not work in my case. I currently only have a grid and no body.
Remesh and “F” unfortunately don’t work, or manually takes much too long with the many errors.
@pxlpaul : That would be great if it works with “Instant Clean - The Ultimate Mesh Clean”. Can you test it? wetransfer: https://we.tl/t-WjCo34NEkr
What the whole mesh looks like?
Wow, yeah, this is going to be a massive pain to work with. Try this (sorry for the wall of images):
Here I’ve royally screwed up a torus to the point where it’s about the same level of problematic as your mesh:
Then I add a cube around it, subdivide it many times, and scale it to fit:
Next, I shrinkwrap the cube to the torus:
I apply the modifiers (shrinkwrap and subdiv), and smooth with 100 repetitions:
I scale the cube up again, add another shrinkwrap modifier, and a Boolean modifier:
I apply both modifiers, add a solidify modifier, and add a remesh modifier:
Now I have a manifold mesh with proper topology that follows the shape of the torus.
Before you ask- how is this different than just remeshing the bad mesh? Well, by creating a mesh with the shape of the bad mesh, but with better topology, the remesh modifier will work a lot better.
Hi Martin,
What is the objective or look that you’re after? This mesh does have many issues. Will have a go at it and see what it can do.
Hi Martin,
I’m afraid I couldn’t get a good result using the Instant Clean addon. But instead I used Quad Remesher by Exoside (see here [$]). It’s the best remesher one can get I believe but it’s not cheap. Here’s a screenshot of what I have so far. Some holes are still there but I think these can be more easily fixed. Still unsure if this is the type of look you are after. Using this you can really see the “sections” in the model. Was this scanned or something? I also turned on Auto Smooth. Let me know if this works for you.
Here’s a quick render using Cycles:
Cheers,
Paul
@joseph This looks good (and cheap), but I don’t understand step 6 “I scale the cube up again”.
@pxlpaul Can you send me back the test file? I want to see if i can process it for 3d printing.
At the final step, I would like to print out my whole neighbourhood and then the city and so on…
Thank you very much for the support, I am really impressed.
Hi Martin,
Ah, it’s for 3D printing. For that I believe it needs to be manifold otherwise I think you’ll run into problems with printing it. So quite a bit of fixing is still required.
Here’s a MS OneDrive link to the zip file with your mesh: Repair Mesh for Martin2 (meshm).zip. The link will expire in 24 hours. The one shown in the previous post is the mesh1.Test.2,Q-Remesh 50K A50% object. There’s another done at 20K (this is the initial target quad count). You might want to Decimate/Remesh/etc… it if you want to reduce the number of faces. Good luck!
Cheers,
Paul