Alignement errors...

[Yoruk]

[Andrea Alessi]

Hello Yoruk,

from your screenshot it actually looks there are no masks involved. Make sure to check "mask images" when you run a reconstruction.

However, your dataset might be hard to run as your subject isn't very textured. Regardless, if you'd like to share the dataset i'd be happy to have a look at it so i can give more specific advice

[Yoruk]

Thanks for this quick answer .

I didn't manage to have any result by working with the mask, I keep having the "something went wrong" message. I have also some issues with the automatic mask computing feature in the "Masquerade" utility. But as you say, maybe it's a texturing problem.

Of course I can share my dataset, but it's a big heavy (160 MB). How can I upload it ? (or were ?)

[Andrea Alessi]

Ah i see, then yes, zephyr fails because the subject is too plain. As it is very uniform, it's hard to find keypoints.

Regardless, i will contact you to the email you have used to register to the forum with credential to our server where you can upload the dataset.

Anyways, you should probably consider adding texture information on the floor to help with the orientation phase, or eventually, you can dirty the surface or - even better - use projected patterns to create keypoints. You can find a tutorial here https://www.youtube.com/watch?v=E06kgYBftak

[Yoruk]

Thanks, I have uploaded my archive to "jpg.zip".

I can upload raw uncropped pictures too if you want (1.07 GB)

Thanks for the video, I got how the pattern projection works, but in my case I absolutely need the object texture.

Can putting a paper pattern on the floor helps ?

[Andrea Alessi]

Hi Yoruk,

never crop or pre-process your JPGs. Please feed images directly as you get them from the camera without altering them. I know it's counter intuitive, but by cropping it you are basically "removing" information from the images. Yes, please update the original photos (even jpgs are fine, no need for the raw, but please upload non-preprocessed images) and i'll see if i can extrract something.

If you need to exclude parts of the images, you can quickly create a mask with masquerade and propagate it to all images.

If need the texture you can do like in the video and take two images, projector on, projector off, use the projector on layer when reconstructing the surface and swap to texture layer for the texturing.

Yes, putting random patterns wills help (avoid repetitive patterns) in the SfM phase

Also, consider shooting with a polarized filter and try using diffused lighting. You can see how the surface changes from red to complete white due to reflections.

As you may have already noticed by looking at the video i linked, your photos are super hard to work with also because:

- there is a lot of noise in your images. Please use ISO-100 or a very low ISO speed. These looks shot at ISO-800 or higher.
- use a better depth of field. Most of the subject is out of focus
- for both the previous two points, consider using a longer exposure time and a tripod, so you can achieve those with ease. Also consider using a remote.
- reflections are too heavy on the subject, so consider changing the lights as well as using a polarized filter if possible

[Yoruk]

Thanks for all these explanations.

I've uploaded the raw images (chaise ballerine_72.zip).

I see how random patterns can help me to increase the alignment phase. But in this case, how to deal with cropping ? I mean, for the alignment step I should keep them, but I will have to remove them after... How can I deal with that ?

Thanks for taking time to examine my problems...!

[Andrea Alessi]

Please do not crop images

You can mask them out, and eventually use the "ignore masking during SfM phase" option.

I'll try your images as soon as i can (hopefully today, or early next week!)

[Yoruk]

Many thanks ! Meanwhile, I'll try to get better pictures.

[Yoruk]

Can increasing the total pictures number helps the alignment analysis ?

[Andrea Alessi]

Yes, it may help, but it's more important that the images are sharp and clear - try to prefer less, good images, rather than a lot, bad images, when possible.

[Yoruk]

Can a camera calibration helps me ?

[Andrea Alessi]

Hi Yoruk,

in this specific case a camera calibration will not help much.

You need good imagesto have a good result, regardless of the calibration used. While a calibration may help zephyr in the first phase (zephyr is completely autocalibrated, but may struggle when the photos are bad) there are still other phases (mvs,mesh,texture) you need to go through.

[Yoruk]

I got it.

About my alignment issues, can putting the object on a non-repetitive object like a pallet helps the alignment ? As the object is low-textured, maybe it can help ?