Create 3d model from photos with manually added reference points


(Coiske60) #1

Hi, new here…

I have a small set (8, from 45° angles) of photos of a monument representing a fist (20 m high) made of flat steel plates.
I have looked to a few programs to create a 3D model from those , but they all propose an automated reconstruction from a lot of good photos. In my case this doesn’t work.
But I can easily detect the edges and joining-points on my photo’s and indicate them
So I would like a free or low-cost program that can recalculate the 3D-model from my set of points. I dont bother about color or texture, it’s the 3D structure that interests me to create a accurate model of this monument. Even just the points, situated in space, will be good enough for me, I can create the planes that are defined by them manually in a 3D modelling program.

If necessary I can take more photos around this statue.

Can anyoçne help me?, Thanks

(I have send the first version of this question too soon, sorry)

(Nebulousflynn) #2

Hello @coiske60 - welcome to Sketchfab and the forum!

You will almost certainly need to capture more images, from many more angles of the monument to get a good reconstruction using photogrammetry software, 50 - 100 images is a good minimum. Here are some free software options:

  • 3DF Zephyr Free - Windows only, max. 50 images
  • Meshroom - open source, Windows + Linux
  • there are also limited demos of Metashape and RealityCapture available, but you won’t be able to export save the 3D reconstruction without paying

Hope that helps.

(Coiske60) #3

hi nebulousflynn,

As you suggested I took some more photos (about 70) from different angles around the monument, and installed Meshroom.
But with about 60 photos of the fist and after several hours I got results that couldn’t satisfy me. About half of the photos were rejected, so I got 3 meshes from the remainig set .
Then I tried with the forearm (just a few vertical steel plates based on a concrete plinth) with 15 photos (from whitch only four where recognized) and I got a result: A mesh (129670 faces) of only one plate and one front of the plinth.
As a matter of fact I don’t need a mesh, just the 3D coordinates of the intersection-points will do.
My aim is to create a faithful 3D model in a CAD-program, so that I can reproduce each of the plates by 3D-printing and rebuild the monument on any scale . (This is the challenge: make a 3D puzzle that can be glued together like a model of a plane by Revell).
I can draw over my photos (on a new layer) the edges or intersection points (and identify them) to make new JPG-files only with lines or points.
In the examples I upload here, you can see what I mean:

  • “Complete.jpg” is a picture of the whole monument

  • “8 photos.jpg” are photos of the fist from 45° angles (I took much more, but these are for an

  • “photos lines points numbers.jpg” are 2 of these photos on which I added lins on the vertices and points on the intersections. I numbered the points to show how to identify them over multiple photos
    then “lines.jpg”, “lines points.jpg” and “points numbers.jpg” show only these elements without the photo
    “cad-model.jpg” is a screenshot from a cad-model I made based on the intersection of horizontal lines starting from some points on the vertically posed 8 photos. I’ts a good start, but very inaccurate, that’s why I want to use photogrammetry.
    So here is my question: can I use the lines and identified points that I can draw based on my photos in a photogrammetry-program?
    I seems to me it’s the very base of those programs, I just want the 3D coordinates of the intersection points.

Thank you for any advise and sorry for the long text in broken English

(Nebulousflynn) #4

Hi again -

Most photogrammetry software will export either a mesh or a point cloud (or orthographic images, or video).

I think you should aim for a complete single mesh from photogrammetry software, exported to your cad software to re-build as a simplified model.

If all the images in your set are not aligning, you need more images with at least 80% overlap between adjacent photographs.

The Metashape trial includes measurement and scaling tools as well as the ability to set markers on images (i.e. link features between 2 or more images) that will help with alignment and mesh output.