Tired of PhotoScan, I Just Want it to Work: 1/N

Subtitle:  Going to ridiculous lengths to understand what doesn’t work with PhotoScan.

I took two sample videos with the GoPro a few days ago, of Dan and Rider.  I want to print a color 3D model of them (shapeways, small), just to see it done, and to have a simple process to do it.   But it keeps not quite working, and its annoying me.   So, here goes another night of experimentation.  What am I missing?

Here’s the precalibration stuff from Agisoft Lens, btw:

Check #1.  How much does it matter how close or how far apart the frames are?

I extracted out at 60fps (the video is 120fps), so I have 1400 frames in a circle.  That’s a lot of frames.

Here are sample reconstructions using just two frames – varying the number of frames apart.  I’m using 4mm as the focal length, but I will play with that in the next section.   Process:  Align on High, Dense cloud on High.    The picture on the right is what Frame # 0 looks like; the screen capture is “look through Frame 0”, zoom out to bring the head in frame, and rotate left (model’s right) about 45 degrees.

 

1 frame apart (cannot build dense cloud) 2 frames (cannot build dense cloud) 4 frames (cannot build dense cloud)	8 frames
16 frames	32 frames
64 frames	128 frames (cannot build dense cloud)
All 8 frames	Above view, to see how the cameras are aligned

Clearly, more pictures is not the answer.    The best one was 0 to 32, which was about a 6 degree difference.

Check #2: Trying every 32 frames, how does adding more pictures improve quality?

This time I’m moving the camera up so I can see the “jaggies” around the edges

3 Frames combined (0,32,64):	4 frames combined:
6 frames combined:	7 frames combined:

The same 7 frames, this time with the wall in view, trying to line up the roof and the wall:

Check #3: Focal Length

Trying to solve for the wall jagginess.

2mm:	4mm:
6mm:	8mm:  Cannot build dense cloud
5mm:
3mm:	4.5:

Okay, so .. 4.5 is wonky, but 4 and 5 are okay?   Its very hard from this angle to see any difference in quality between 3,4,5 and 6.   2, 7, and 8 are clearly out**  

Maybe another angle:

3mm:	4mm:
5mm:	6mm:

** Or maybe 7 is not quite out yet.  Turns out, I can “align photos” once.. get one result.. then try aligning again .. and get a different result.   So I retried 8 a couple of times over, and I got this:

None of this is making any sense to me.   I guess I’ll stick with 4mm, for lack of a better idea.  Do you see any patterns in this? Moving on.

Check #4:  Low, Medium, High Accuracy?

I’ve bumped it up to 17 cameras (32 frames apart).  Testing for “Align Photos” accuracy (Low, Medium, High) + Dense Cloud accuracy + Depth Filtering

High, High, Moderate	Low, Low:   Cannot build dense cloud. Medium, Medium, Moderate
High, Medium, Moderate	High, High, Mild:  (Mild took around 3 minutes)
High, Ultra-High, Aggressive:  (12 minutes)	Close up of H/UH/A:

Aggressive is definitely the way to go; however, there are still way too many floaters!

Ah, but this image might clear that up a bit.   It has to do with the velocity with which I was moving the camera.  I slowed down.  Hence several of the frames are not very far apart.   I might need a different approach for frame selection.

Test #5: Compass Points Approach

I will attempt to bisect angles and derive frames in that manner.  Note that I’m not going to try the full 360 – I suspect that the subject moves a bit, so it can’t connect 359 back to 0;  instead, I’m hoping to get a nice 90 degree profile, and maybe merge chunks to get it down to a single model.   So lets try to get a set of frames from the image on the Left (000) to the image on the Right (400).

• 0,200,400 – Aligns 2/3
• 0,100,200,300,400 – Aligns 5/5, but fails to build dense cloud
• 0,50,100,…,350,400:

I have to cut this blog post short here – it looks like I have WAY too many images, and Live Writer is freaking out.   Doing a quick edit past, and then posting this as a part 1/N.