How can I make a manual mask for edge blending of unaligned projectors?

[artboy]

Hello. Everyone on the forum

I want to hear from you.

The automatic edge blending of the watchout works great when the projectors are horizontally and vertically aligned.

However, when the projector is not aligned, automatic edge blending is applied in only one direction, and normal edge blending is not possible.

For this reason, I have to create a manual mask in the stage-mask tab or create a mask in another program and use it.

The manually created mask does not properly handle the corners where the mask overlaps, resulting in poor blending effect.

Can you share some tips or how to create a mask?

 

[Mike Fahl]

You can add custom masks inside the Display Settings dialog box (assuming you use WATCHOUT 6). See under MASKING in the DISPLAYS AND PROJECTORS chapter.

Note that it's not possible to create a "good" mask for the arrangement you show above. The pixel at the intersecting edges must be 50% intensity, meaning that a 1 pixel error in alignment will be visible in that area. That has nothing to do with WATCHOUT and everything to do with physics.

Mike

[artboy]

Hi. Mike. Thanks for the answer

I don't want'good' blending for the current situation.

However, I would like to prevent the black areas from becoming prominent or forming lines when masking is performed using the manual mask generator.

Manual mask generation is likely to be used frequently in cases other than the examples provided. I would like to talk with the members about production tips and methods for these cases.

 

And if you are okay, please explain more about 'The pixel at the intersecting edges must be 50% intensity, meaning that a 1 pixel error in alignment will be visible in that area'.

[Mike Fahl]

Consider two edges that cross, forming a "corner". Each pixel in this corner, coming from each of the projectors, must be at 50% brightness, for the combined brightness to come out as 100%. The pixel next to this, just outside the blended area, must be 100%, since there's no blend there. Now, if you move one of the projectors by 1 pixel, you'll have a very notceable 100+50=150% brightness right there, clearly visible as a bright line.

Hope this helps.

Mike

 

[RBeddig]

As Mike said, it's physics and a calculation problem.

If display 1 and 2 would be in one horizontal line, you would add a logarithmic gray curve to both sides. On D1 it would start with 0% on the left going to 100%, on D2 it would just be the opposite.

Now, in your case you also have a vertical blend. So here the mask on D1 would start at 0% on the top going to 100% at the bottom of the overlap. On D2 it is vice-versa. If you now look at the pixel in the lower corner between D 1 and 2, the mask should be 0% for the horizontal mask and  at the same time100% for the vertical mask.

The only way to get a correct overlap would be to use camera calibration system.

E.g. domeprojection.com    https://www.domeprojection.com/products/demo-version/

[artboy]

Thank you for Mike & RBeddig

In camera-based calibration systems, I have seen that a suitable blending mask is created in a similar stage configuration.

However, using a camera-based calibration system may not be possible depending on the site. To prepare for this, I am looking for a way to manually create a mask in WATCHOUT.

In theory, it makes sense, but the WATCHOUT MASK tool has a lot of limitations.

As RBeddig said, creating a mask for a sample requires a combination of top and bottom gradients and left and right gradients. However, using WATCHOUT or Photoshop is not easy.