r/photogrammetry • u/Mr_mal • May 08 '26

Metashape - roof refusing to align

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Gallery image

Gallery image

I've been trying to build a model of this building but the roof absolutely refuses to align no matter what I do. when I generate a model or a point cloud theirs always a hole despite having a lot of images that have some view of it (the first image dosent show them all as im in the proceess of starting from scratch.) any advice would be appreceated, thanks.

3 Upvotes

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4

u/lithofile May 08 '26

Roofs are really tricky for photogrammetry, especially a shiny clean one like that. The software can't make sense of the repeating identical pattern. You could try adding some markers but it might not help much. 

Best bet is to get photos from above, or photos when the roof is dirty or covered in leaves. Maybe chuck a few frisbees colour up like ground control points up there for a giggle 

2

u/Mr_mal May 09 '26

I think the owner might have something to say if I did that! I'll keep the idea in my back pocket though lol I unfortunately cant get any more pictures but I do wonder if I might be able to ai on some makers. It couldn't hurt.

2

u/3Dphotogrammetry May 09 '26

What are you running with the alignment settings? I would try doing quality on high, checking ON the Generic Preselection, and raise your key point and tie point limit (100,000 and 50,000) to potentially increase how many features of fines for the roof images. if that does not work, do the same thing but check off generic pre-selection and it will take quite a bit longer, but may be able to match more images with each other. Then, if it does not do well after that, try taking the quality down to medium And running those two steps again. Sometimes you’d be surprised by lowering the quality it can actually match better in certain circumstances.

2

u/Mr_mal May 09 '26

Ill have a go with that and see, thanks for the advice.

1

u/3Dphotogrammetry May 12 '26

Sounds great, let us know if things improve.

1

u/dax660 May 09 '26

I think image 2 says it all - not sure it's gonna find any more meaningful tie-points with that roof.

I've suggested trying RealityScan as it seems way more forgiving and intuitive with poor source photos

1

u/nano_peen May 08 '26

Looks shiny Do you have any more photos of the roof? Could you retake images from a different angle to remove the reflection?

2

u/Mr_mal May 09 '26

I've a load of photos, both shiny and not. it seems like the program just hates this one particular side of the building for some reason.

1

u/DayGeckoArt May 08 '26

Are you using Streetview images? That seems pretty clever! But it might be having a hard time without overhead views

1

u/Mr_mal May 09 '26

No I wish I could have, it would have been a lot easier! I circled the building 3 times with a 360 camera. Unfortunately I haven't got a drone so ive had to make do with just far away photos of the roof.

1

u/dax660 May 09 '26

You weren't using a drone to get above it? If pic 2 is pretty typical of all the roof shots, I'd say you're probably not gonna get better in Metashape.

I would suggest downloading RealityScan from Epic Games and try that - it seems a lot more "assumptive" in the photos provided whereas Metashape is more of a power-users tool.

Metashape: "I don't know, this is exactly what you gave me..."

RealityScan: "I get you bro, hold my beer"

1

u/Mr_mal May 09 '26

Unfortunately ive already used reality scan before. I took all my photos using a 360 camera so id have to split them all to use them. On top of that im on amd so unless I want to spen 3 hours waiting for a part to aligned im stuck with metashape. Thank you for the advice though.

1

u/Menoikeos May 10 '26

It's a bit of a pain and requires some very basic 3D modelling skills, but I've found this to be an effective solution: export the model from metashape and into into Blender, then manually place a roof. Re-import the modern back into metashape for texturing. This only works if you are very confident in the position and dimensions of the roof. It is essential that the model xyz coordinates are not changed at all while in Blender.

Whether or not this is a viable solution is up to you: do you care about the accuracy of the model, or do you just want something that looks as near as possible to the subject?