I was experimenting with telecentric Nikon MM 10x measuring objective pushed down to lower magnifications than its designed m. Stacking was in Zerene. I knew it would no longer be telecentric when pushed down to a wider FOV, but still I wanted to see what would happen if I turned off scaling in Zerene. Zerene's reported scaling factor near the end of these stacks was around 1.01 so definitely not telecentric. With scaling turned on, there was almost no difference between the resolutions of the images produced by the two stacking options, PMax and DMap, and both showed the fine ridges on the butterfly scales. When I turned scaling off, I still got quite good resolution of the ridges using PMax, but in DMap I lost most of them. This was a curious result which I do not understand.
You may wonder why anyone would turn off scaling when the lens is not telecentric. I would want to do this when I need to stitch several stacks together, to avoid artifacts. I am sure this produces its own artifacts, but these might be manageable.
Here are the two images with scaling turned off, blown up to 200%; on the left is PMax and on the right is DMap. Both are made from the same stack. Pardon the purple fringes, the MMs have a lot of that. You can see that the PMax image shows good ridges on the scales, but these are largely lost in the DMap image.
Zerene: Difference between DMap & PMax with scaling OFF
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- rjlittlefield
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Yeah, me either.This was a curious result which I do not understand.
The characterization "difference...with scaling OFF" is one that I have not seen before. I strongly suspect that what you're seeing is due to some other cause that is just coincidentally correlated with scaling.
To briefly review, DMap works by selecting pixels from individual as-adjusted source frames, as indicated by the depth map, or forming weighted averages of two adjacent source frames where the depth map is transitioning between source frames.
When DMap misses detail that is present in some source image, it must be that the depth map did not select that image. Common causes include estimation radius and/or smoothing radius too big, and/or contrast selection slider too far to the right (too much "black in preview").
If this stack were sitting on my computer, the first thing I would do is to compare the as-adjusted source images against the DMap output to try identifying how the depth map had gone wrong.
It is best to do this in retouching mode. That's because when not retouching, the source image panel is likely to be showing a low quality "screen preview" image rather than the full quality source image. In retouching mode you also have the S key to flash between source and output to facilitate comparisons. To get faster transitions between source frames, it helps to select one of the advanced brushes such as Pixels.
From what I can see here, it looks like maybe the depth map is properly tracking the high contrast edges of the scales, but not the lower contrast bases and interior areas where the fine ridges are.
--Rik
Last edited by rjlittlefield on Fri Oct 06, 2017 2:19 pm, edited 1 time in total.
But with the very same source images, there is no difference between DMap and PMax when scaling is left on. I'm not sure what I should look for in the adjusted images....I'll re-run the stacks now.I strongly suspect that what you're seeing is due to some other cause that is just coincidentally correlated with scaling.
OK I've redone the four stacks, using every fourth frame.
The result is just as I presented above. When Scaling is checked, there is no difference in resolution between DMap and PMAx outputs. When Scaling is unchecked, there's a huge difference in resolution between the two outputs.
Also, comparing PMax outputs alone between "checked" and "unchecked", there very little resolution difference.
All these are done on the exact same set of source images.
The result is just as I presented above. When Scaling is checked, there is no difference in resolution between DMap and PMAx outputs. When Scaling is unchecked, there's a huge difference in resolution between the two outputs.
Also, comparing PMax outputs alone between "checked" and "unchecked", there very little resolution difference.
All these are done on the exact same set of source images.
- rjlittlefield
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- rjlittlefield
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- Posts: 23606
- Joined: Tue Aug 01, 2006 8:34 am
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- rjlittlefield
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- Posts: 23606
- Joined: Tue Aug 01, 2006 8:34 am
- Location: Richland, Washington State, USA
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Most people would upload to DropBox or send via wesendit.com, but I'm pretty sure that 3 GB at one time would exceed their limits.
If you want to send DVD, the best place would be the address shown at https://zerenesystems.com/cms/about_us .
For reducing the frame count, try first just restricting the stack to be the images contributing sharpness to the crop that you've shown.
--Rik
If you want to send DVD, the best place would be the address shown at https://zerenesystems.com/cms/about_us .
For reducing the frame count, try first just restricting the stack to be the images contributing sharpness to the crop that you've shown.
--Rik