weird camera positions

Development Asset Creation
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1

Hi,

I was doing some turntable test again - this time with a shoe.

I followed the suggestions from earlier threads: 50 mm instead of 18 - and I managed to crop most of the background in Lightroom so cr wouldn’t get confused by it

First I put the shoe in a normal position which gave the expected result:

Then I turned the shoe 90 degrees to be able to scan the sole - this is what the camera positioning looks like:

and this is how the model of this component looks like

at first, I thought the shoe might have “slipped” a bit on the turntable during the process… but then again it should not matter if the shoe moved between shots, right?

Any suggestion what might have gone wrong?

Thanks !

2

Hi Heiko,

you are right, it should not matter if you eliminated all background that could have shifted in relation to the shoe.

Which images did not get aligned? Is it possible it’s the sole? Does it provide enough texture?

Do you polish your shoes or just wear them down? :-)  too shiny will not help RC.

Anyway, I think that a handful of strategically placed control points might give RC the small push it needs to get it right…

3

never had much luck with control points so far - but I think its a matter of practice. I’ll try that - thanks.

Ans yes: shoes are pretty worn - no shiny surfaces and overall there should be enough details to pick on

 

4

If the image set isn’t too big, I could have a look at it.

We said we should work together, to get some how-tos going so we might as well start here…  :slight_smile:

5

appreciate the offer - however, for the sake of practice and experience, I just went through the whole process again and now I’m pretty happy with the result.

https://skfb.ly/6wYHY

DataSet here:

https://www.dropbox.com/sh/4vwt1idoh99dmtz/AADo7hC4zbMYSgUCh3TeIN3la?dl=0

the only thing that I don’t get is why at the back of the shoe it gets so bumpy - besides that: close to flawless

 

6

Again, it’s not bad.

What did you do differently this time? Just gave it another go? If yes, then it prooves that the set is boderline to working within RC and it needs some more shots to stabilize the geometry.

The “bumps” are caused by a small misalignmen, that means that not all the cameras that cover this area are connected properly (use the inspection tool to identify them). There are several more misalignments, e.g. the sole at the tip protrudes. You can prevent that by connecting the sole to the top at more places, either by a few CPs or more images…

7

I took the photos at F10 or 11. before that I was going with well over 20 - hoping for better dof. However I learned that that was well beyond my lenses sweetspot and probably counter productive.
It’s a good hint that those bulmps can be fixed with more fotos. I’ll try that.
A few photos have less than the intended 40.000 tie points. Does that also hint to something ?

This is the result of the inspection:

would it be a correct assumption that I need more photos on the tip and the back of the shoe since it is so narrow compared to the sides ?

8

Yes, more and you might also want to fill your frame better - the object should fill about 80%.

Also, I would suggest not as many shots on the long side on one level, but rather circle around  the longitudinal axis and the perpendicular axis.

Fewer features can be an indicator for a blurred photo or just not enough textured surface.

9

What I did is : the turntable goes 9 degrees a second. I take 1 photo every 3 seconds - 40 times.
I was Trying to automate things as much as possible.
Again : thanks for your advice. I’ll work on my photography skills :slight_smile:

10

A constantly moving turntable is rather bad for photogrammetry as you are pront to getting motion blur with those.There are, however, a few turntables out there that are programmable and that even trigger the camera for you.

 

I’ve linked you the one I use for many of my scans below as an example.

https://www.amazon.co.uk/gp/product/B011JAIYRA/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

You can set the degrees it rotates between stops and the delay in seconds. It does trigger the camera and automatically stops after one turn.

11

Thanks - exactly what I was looking for. I mad up for the motion with fast shutter speed - for learning that was quite ok. But I know that moving during shots was an error source.