Tips for 3D scanning individual plants

[mrcjago]

Hello

I am fairly new to using Metashape and 3D scanning/photogrammetry in general. I am currently using the standard version of the software.

I am struggling to successfully create a model of a small plant (basically a twig with some leaves, possibly flowers etc.).

I've attached some example images I took recently. All, apart from the image ending in 84, failed to align properly, and the image ending in 84 had a ton of noise.

I'm assuming (please forgive me if I am completely wrong) that some of the factors that made these fail are: lighting not being flat enough, leaves being too smooth/shiny and lacking texture, too much detail in the plants etc..

I tried masking a couple of the images from the set which the image ending 68 belongs to (there were about 40-50 in total), and then selected apply masks to tie points when aligning, but that didn't work so well.

I've had success with other subjects but individual plants seem to be really tricky...

I just wondered if anyone had tips for someone fairly new to this for successfully scanning a plant of some kind - do some plants work better than others for example? Should I spray them with something to add texture?

Also for reference, my set up is basically having the subject on top of a lazy susan which I turn in increments, the background is white or green paper and remains static. I'm having to do a bit of a make-shift set up, usually I can do all my scanning at my university, but since we are on lock-down, this is the only option I have...

Any help or advice would be really appreciated,

Thanks!
Christian

[danderson4]

can you post some screen shots showing what you get when you align photos? When you say that it fails, how does alignment fail? Only some align? Or to they all align in one location?

I think what is happening is that Metashape is "locking onto" you  background.  you want to have your background as uniform as possible without any features visible and preferably also out of focus.   I use a black background which is at least 40 cm behind my subject.  I adjust my f-stop to give  a good depth of field so the entire object is in focus but the background in out of focus (f16 or higher) and a low ISO 100 or 200.  I then allow my camera to adjust the shutter speed.  I also may adjust the aperture to "stop down" a few thirds of an f-stop if need to get a good uniform background blackness.  Attached is a photo from one of my turntable sessions. You can see how there is nothing visible in the background for the software to lock onto.  The clay and the target are on the lazy Susan and turn with the object.

My other thought is that the leaves are moving slightly from one photo to the next as you turn and so they are never in exactly the same position.

Hope this helps

[stanlichens]

HI_ I am having a related problem in scanning a plant- in this case a fern frond. I shoot them against a white background, and the white becomes part of the shot, looking like a white cloud surrounding the plant. Should I be shooting against black then? Any insight into this would be very helpful. thank you, Stan

[Alexey Pasumansky]

I have seen on Sketchfab some nice examples of pot flower models, processed in Metashape:
https://sketchfab.com/3d-models/red-rose-74520e87c3ed46898668c83356dd9cfa
https://sketchfab.com/3d-models/hoya-australis-f4d7ceb2804149d7b847de9964fc738e
https://sketchfab.com/3d-models/aster-alpinus-b41ad788f177422192a1df5201ceab03
https://sketchfab.com/3d-models/episcia-cupreata-2e08eed528f149b8b057fb0516ab467e

The important thing is to provide very good overlap, in order to have stable complete alignment of the dataset, and to have almost complete coverage - having images taken from all possible sides in order to minimize the blind zones.
If you think that your dataset fulfills both criteria, you can share it to support@agisoft.com, so that we could take a look.

Of course, general recommendations should be also fulfilled, like good focal depth, high image quality, low noise and etc.

[DmitriB]

can you post some screen shots showing what you get when you align photos? When you say that it fails, how does alignment fail? Only some align? Or to they all align in one location?

I think what is happening is that Metashape is "locking onto" you  background.  you want to have your background as uniform as possible without any features visible and preferably also out of focus.   I use a black background which is at least 40 cm behind my subject.  I adjust my f-stop to give  a good depth of field so the entire object is in focus but the background in out of focus (f16 or higher) and a low ISO 100 or 200.  I then allow my camera to adjust the shutter speed.  I also may adjust the aperture to "stop down" a few thirds of an f-stop if need to get a good uniform background blackness.  Attached is a photo from one of my turntable sessions. You can see how there is nothing visible in the background for the software to lock onto.  The clay and the target are on the lazy Susan and turn with the object.

My other thought is that the leaves are moving slightly from one photo to the next as you turn and so they are never in exactly the same position.

Hope this helps

thanks for sharing your process. Very interesting - do you allow the camera to keep adjusting the shutter speed during the photoshoot?
Thanks