Bumpy suface

[Brit]

"the entire object doesn't need to be visible in the frame." That is good to know! So just part of it will work, as long as all of it is in some frames?

[bigben]

Yes, and there's plenty of overlap so that each point on the object is in at least 3 images.

[Alexey Pasumansky]

Hello Brit,

The basic principles of image acquisitions and pre-processing are the following:
- do not crop original images,
- do not apply geometrical transformations (rotations or deformations) to the images,
- use image frame effectively,
- provide sufficient overlap and coverage of the surface being reconstructed.

Additional recommendations:
- use lower ISO values,
- provide good focusing and sufficient focal depth to acquire sharp images,
- avoid using flash,
- if different focal length are used, make sure that cameras are grouped correctly into calibration groups (in Tools Menu -> Camera Calibration window).

Masking can be performed semi-automatically - at first you can generate masks from model and then adjust them manually.

[Brit]

Thank you for all the help!

[Brit]

What do you mean by: "Masking can be performed semi-automatically - at first you can generate masks from model and then adjust them manually."?

[Alexey Pasumansky]

Hello Brit,

I mean that you can build rough model, use Import Masks -> From Model option, then adjust automatically generated masks manually.

[Brit]

It what you are saying that I make masks roughly in Photoshop, then it is easier to adjust the masks more accurately in Photoscan?

[meshmixup]

Hi Brit, what Alexey means:

1. Align the photo, dense cloud and build the mesh without any masking
2. The generated mesh is roughly formed
3. Now, select the import mask -> from model! you can see the photos are masked with the rough model but not very fine
4. Then you can check the photo and edit the mask of each photo manually.
5. Once you have edited a better set of masks, you can re-run the process again 

[Brit]

1. Align the photo, dense cloud and build the mesh without any masking
2. The generated mesh is roughly formed

3. Now, select the import mask -> from model! you can see the photos are masked with the rough model but not very fine

This is the part I am unclear about - in order to import masks, I need to have masked all the photos in advance. I though that this method was to avoid making detailed masks? Do you mean > mask the images, then import and build cloud and mesh without the masks first? And then import the detailed masks?

4. Then you can check the photo and edit the mask of each photo manually.

How do I edit masks once they are imported (and the mesh is already made)? 

[DCK]

Holy crap. I've always masked before alignment. I just tried the procedure above: aligning, making a mesh, and building a texture model, all prior to masking.

The results are excellent. My question now is, WHY MASK AT ALL?

I shot my images against a black background, with the object mounted on a ball of plasticine and rotated on a turntable. As you can see from the attachment, PhotoScan picks up a few pieces of the plasticine and background, but I could easily cut these away without compromising my model.

Seriously, why mask at all?

DCK

[meshmixup]

Hi DCK, I think as your object is placed in controlled environment, you can easily take background photos and do masking nicely. Even without masking, i think you can still generate good results. So masking prior or after gives similar result.  But sometimes it is not possible to take background photos or there are other unwanted objects in the photos such as moving people. The above procedures can help to mask out these factors based on the rough model. But do not expect the masking result is very accurate therefore you have to modify it manually

Hi Brit,
3. no masking -> align photo -> generate dense cloud -> generate mesh -> import mask -> from model. Done!
4. click the photo, you can edit the mask with the buttons given on the tool bar. just like photoshop
5. re-run align photo...... again. The model will be regenerated will new mask information

Anything I am missing or incorrect? 

[Brit]

Darn, I just spent 2 days (off and on..and until midnight last night) masking 85 images of a building -with a lot of obstructions such as signs and cars as well as people in front of it. After trying to produce the mesh from these, I'm not sure that I'll have the stamina to try again with his new method. ...Which I still can't get my head around for now....

[Brit]

I aligned the masked photos ...and came up with this the 2 sides of the building crossed in an x. any idea how to get them aligned correctly?

[bigben]

I occasionally get this, and have seen it in many posts.  There's usually 1 or 2 things to do to fix this.

Firstly, check the chunk info and see how many images are not aligned.
Select these images (the ones with NA next to them), right click on one and "align selected cameras". You usually find that a number of them will become aligned.

Secondly, rerun the image alignment.

In the attached screen grab the images that didn't align are at the end of the laneway. So one set of images aligned together quite nicely, but there was no overlap between these and the other images, so you effectively end up with two nicely aligned point clouds in random orientations.

Final model:
https://sketchfab.com/models/c0c1934004f14221b87c38e0e9bba820

[Brit]

Hmm I did notice that the numbers were not in order in the cameras folder.. What could this be about? 

but now I understand how to edit masks later in Photoscan. It is still much easier in Photoshop.