Is there a problem with black objects in the Free version?

[Valandar]

I took about 40 photos, at various angles, of a black, simple bicycle helmet. Loaded them into Zephyr... and, well, you can see what I got.

https://i.imgur.com/sMLIj8Y.jpg <-- The helmet

https://i.imgur.com/WuHUHlZ.jpg <--- The result.

Should I cover it in blue painter's tape or something? Is there something I should have done but did not?

[Andrea Alessi]

Hi Valandar,

that is sadly a common issue with photogrammetry in general

Photogrammetry struggles with uniform textures. Zephyr works by matching pixels, which means zephyr has to understand where the pixel (X,Y) in image A is found in imageB, imageC and so on. Moreover, a little glossiness (like the white highlight you have) are also a problem, as a "pixel" it expects to be black, in an image it become a little whiter. This is usually not too much of a problem if the object is rich of textures, but in case of uniform colors, it's a bit of a problem.

You have a few options:

1. dirty the subject (for example, dirt, dust, chalk or any other powder)
2. use a pico-projector to project a random pattern on it. This is usually done when you only need the geometry, or if you have a fixed camera rig which will allow you to take two photos from the same spot (and change the workspace images at the texturing phase)
3. use the shape from silhouette (requires zephyr pro) approach

the reconstruction engine between free/lite/pro/aerial is the same, so running the same photos with the same setting would yield a different result.

The easiest route would be to dirty the subject =)