High Definition 3D model of a 30cm. statue in a museum...

[Cyber Simon]

Hi everyone! I have to make a 3D copy of this ancient statue (it is 30cm. tall) for a local museum, and I would like to get best from our beloved Metashape!!!
I have few questions and I will be grateful to anyone will spend some minutes to help me 🙂

1) is it better a new phone with 64megapixel camera or an old Nikon D7000 with a good lens?
2) my best lens is a 85mm Nikon f 1.8, (that I read I should use at 7/8 to get better depth detail)
3) I also have a Sony a6000 mirrorless with stock lens that I used only for streaming... is it better than Nikon or phone?
4) I will be in low light (a restorer workshop) should I put my light on tripod around the table or fix them to the camera and have light moving with me around the object?
5) I have experience mainly with drone and monuments, so any hints will be highly appreciated... 🙂 🙂 🙂

Thanks in advance, greetings from Italy and congratulations for making this Great software!!!

[jenkinsm]

a6000 is higher resolution so that will be better than D7000

Phone cameras have extremely small pixels compared to larger DSLRs and mirrorless cameras. This produces sub-optimal results with Photogrammetry. If you had to use a phone camera, you'd be better off with 12 MP than 64 MP.

Since you have a better lens for your Nikon than your Sony, consider getting an adapter that will let you use the 85mm prime lens on the Sony body. That said, 85mm is very tight and it will mean you need to take a lot more photos to capture your full object. But that would also result in higher quality.

I'd probably put the light on the camera and have it move with you around the object. A ring flash would be ideal. And you could also experiment with cross-polarization!

[Bzuco]

1/2)
D7000 with 4928x3264 photos is enough for 30cm statue. With your 85mm lens you will be ~2m far from statue. In portrait/landscape mode you can achieve almost 0.07mm per pixel, which is way more you need.
7/8 f number gives you depth and also sharpness in corners and sides of photos and also chromatic aberation is almost eliminated. Higher f numbers starts produce overall less sharpness, so you can find some sweetspot for your lens( start test f from 4.0 - 11).

4)
For bad light condition I would try 5 big white papers around statue(top/bottom/left/right/back). Put one or more light behind papers or infront of statue. This setup can give you good ambient light. One light mounted on camera could potentialy create some shadows on statue as it cannot be mounted exactly on lens/chip axis position.

Will you be able to put statue on turntable, or manually rotate it on table, or is the statue somewhere fixed on wall?

[Cyber Simon]

1/2)
D7000 with 4928x3264 photos is enough for 30cm statue. With your 85mm lens you will be ~2m far from statue. In portrait/landscape mode you can achieve almost 0.07mm per pixel, which is way more you need.
7/8 f number gives you depth and also sharpness in corners and sides of photos and also chromatic aberation is almost eliminated. Higher f numbers starts produce overall less sharpness, so you can find some sweetspot for your lens( start test f from 4.0 - 11).

4)
For bad light condition I would try 5 big white papers around statue(top/bottom/left/right/back). Put one or more light behind papers or infront of statue. This setup can give you good ambient light. One light mounted on camera could potentialy create some shadows on statue as it cannot be mounted exactly on lens/chip axis position.

Will you be able to put statue on turntable, or manually rotate it on table, or is the statue somewhere fixed on wall?

Thsnks very much for the advices! I will use mainly the Nikon and I also bought today the 50mm f1.8, because I made some tests and cannot take photos from the top at long distance, as the statue will be on a table and I have to use a tripod. Today I was shoting at 1/20 sec time to have low ISO and f8-9.

I am curious about the white paper walls... do you think that having no backgroung at all is best or worse for Metashape to calculate points... I read that it is more precise with a detailed background.

If I can use a white wall I would prefer.

The statue will be on a table, horizontal. I wont be allowed to move or turn it. It has about 2300 years and cannot be moved much.

My idea is to take a full set of photos with it facing up, and then ask to turn it upside down and make another set of photos of the other side

[Cyber Simon]

a6000 is higher resolution so that will be better than D7000

Phone cameras have extremely small pixels compared to larger DSLRs and mirrorless cameras. This produces sub-optimal results with Photogrammetry. If you had to use a phone camera, you'd be better off with 12 MP than 64 MP.

Since you have a better lens for your Nikon than your Sony, consider getting an adapter that will let you use the 85mm prime lens on the Sony body. That said, 85mm is very tight and it will mean you need to take a lot more photos to capture your full object. But that would also result in higher quality.

I'd probably put the light on the camera and have it move with you around the object. A ring flash would be ideal. And you could also experiment with cross-polarization!

Yes, Today I made some tests and with the phone I got much worse results than with Nikon. Sadly I dont have an adapter, but I read that the stock lens of Sony are not bad. So I guess I will make 2 full sets of photos (one with Nikon and one with Sony!). I will have time!

[Bzuco]

You can put some small marks(or print small metashape markers) on white paper, the main purpose of papers is ability to lit the statue evenly...like in exterior on cloudy day...and eliminate all shadows. If the statue covers almost whole field of view, then it should be no problem align photos even without markers.
White background is also good for automatic pointcloud cleaning, because you can choice all white points and delete, and also it can improve exposure time when taking some photos from top angles without tripod.
If the statue is on table, you can try one paper with markers put on table and bend secont paper (1.5m x 0.5m) behind statue as standing half ring and rotate the bended paper as you will be moving around table.

[Cyber Simon]

You can put some small marks(or print small metashape markers) on white paper, the main purpose of papers is ability to lit the statue evenly...like in exterior on cloudy day...and eliminate all shadows. If the statue covers almost whole field of view, then it should be no problem align photos even without markers.
White background is also good for automatic pointcloud cleaning, because you can choice all white points and delete, and also it can improve exposure time when taking some photos from top angles without tripod.
If the statue is on table, you can try one paper with markers put on table and bend secont paper (1.5m x 0.5m) behind statue as standing half ring and rotate the bended paper as you will be moving around table.

Thanks very much for the informations!
Today I made a test with markers and it was much better than yesterday!

I have a new question: do you think that I use markers on the table I do not need background for alignment? Then you think I can use white backgroung in all photos?

We will be 2. So my friend can help me to keep a big white paper behind. Do you think this will be better?

Really big thanks to everyone for the advices

[Bzuco]

Some tutorial with printed coded targets, maybe you already read it.
https://www.agisoft.com/pdf/PS_1.0.0_Tutorial%20(IL)%20-%20Coded%20Targes%20and%20Scale%20Bars.pdf

I have a new question: do you think that I use markers on the table I do not need background for alignment? Then you think I can use white backgroung in all photos?

Statue itself is full of feature points for metashape, only if the statue on photos would be very small, then it would be bad for alignment process. Markers are good if something goes wrong with few cameras during alignment.
You should use white paper ring on all photos, because you want to achieve as much as possible good color and brightness representation of statue.
I don't know how the room and table looks like, but if the table is just uniform colored and the rest of the space(room) will be poorly lit, then the "background" would not help alignment process much.

We will be 2. So my friend can help me to keep a big white paper behind. Do you think this will be better?

Yes, if you don't have some good studio equipment, your friend will be very useful

You can try adjust the camera exposure so that the bended paper starts to be slightly overexposured, so it will not distract metashape alignment process. As you both will be moving around the table, be sure that bottom paper and bended paper will cover whole camera view (only feature points from markers and statue should be as source for metashape alignment,... no hands or objects behind papers).

[Kiesel]

Cyber Simon,

Don't forget to put in the scene a color reference target and some scale bars like these:
http://palaeo3d.de/WP/?page_id=23

You might also find some helpful tutorials on Dr. Heinrich Mallison's page, even most of them are a little older now:
https://dinosaurpalaeo.wordpress.com/author/heinrichmallison/



Best regards,

Kiesel