# Strange artefacts when using Decimate modifier

While using a decimate modifier, I get these weird shading artifacts:

I have managed to narrow it down to the Decimate Modifier causing the problem.

• What is causing this weird shading?
• How can I avoid it / how to fix it?
• How can I keep the low poly count without doing it manually?
• Subsurf followed by decimate doesn't seem like a good idea to me. Anyhow, these artifacts can have multiple causes. Try recalculating the normals after applying the modifier (CTRL + N in edit mode, with everything selected) or removing doubles from the mesh. – IAmGettingTiredOfAliases Dec 17 '18 at 17:57
• @IAmGettingTiredOfAliases I have tried that before and tried it again, and it still leaves me with the artefacts. I have a subsurf because my original mesh is low poly, and then I want to smooth it, so the decimate is meant to reduce that new poly count. – George_E Dec 17 '18 at 18:02
• This probably pins it down to a problem in topology. In that case you could go and try to reducde the (inevitable) horrible geometry left by the decimate modifier yourself. I'm assuming that it's caused by NGons which really don't like the way they're being bent, I am not completely sure to be honest. I'd greatly appreciate it if you could upload the file for me to tinker with! – IAmGettingTiredOfAliases Dec 17 '18 at 18:11
• @IAmGettingTiredOfAliases I was just fixing it now. It didn't have and ngons, it was a warped grid because I was using the ANT landscape add-on. I am just applying "dissolve vertices" on every point where the issue occurs and it is fixing the problem. – George_E Dec 17 '18 at 18:24
• Alright! Glad you could get it fixed, good luck with your project! – IAmGettingTiredOfAliases Dec 17 '18 at 18:27

The fix was actually very simple, and I did not need to remove the Decimate modifier. All you need to do is just x> "dissolve vertices" in Edit mode on every point where the issue occurs and it will fix the problem.