Photogrammetry lighting question

[cheis]

Hi there,

 

I am very new to photogrammetry and I have a question an image capture/lighting question. 

 

I'm wanting to do photogrammetry on a somewhat large indoor sculpture.  I will be working in the round, but I am going to have to use external flashes on stands for lighting.    I only have 2 lights at my disposal.  

 

My question is,  will I need to move the lights around the sculpture incrementally (every ten degrees or so) as I also reposition the camera by moving around the sculpture?  Or, can I leave the lights in more of fixed position, and move them when I'm say at every 9th camera position, assuming there are 36 camera positions? (ie every quarter of the way around)

 

Thank you in advance.

Crystal

[cdschroer]

It's hard to answer this without understanding more about the subject and about your lighting setup.  I'l give some general advice though.  The key thing you want to avoid is moving shadows.  The matching software in photogrammetry can try to match pixels using shadow lines, and if these are moving around, you may not get a good alignment, or a bunch of stuff may be in the wrong place.

 

We recommend using soft boxes or umbrellas on your lighting (or diffusers, depending on your lights)  Then look in terms of what is lit, and whether you have shadowed areas, and how those are affected as you move around the subject.

 

I'll also note that you should plan to do more than one circuit around your subject.  Three circuits is kind of a minimum to get enough look angles (redundancy) and more may be required, depending on the size and shape of your subject, how far away you are with what field of view, etc.  

 

Good luck!

Carla

[cheis]

Thank you Carla.