Composite with Polygon Mask

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Marpel
Posts: 692
Joined: September 13th, 2009, 3:19 pm
What is the make/model of your primary camera?: Nikon D810
Location: Port Coquitlam, British Columbia

Composite with Polygon Mask

Post by Marpel »

Latest version. Image 4912 X 7360.

Two images, only difference one a darker version of other.

As I wished to composite a section of one into other, and the section was the left area, with the dividing line (straight) from about one third of the image over from the lower right, to about one fifth in from the upper left corner (an angled vertical line so the masked area was a tall triangle, cut off a bit at the top), I used the Polygon Mask Tool.

Started by clicking above and to left of image's top left corner (don't know if it's relevant, but to do so, reduced the image size one step to be able to click outside the image). Dragged the mask to the right and down until the bounding box encompassed the area to composite. At this pint, all four corners of the box were outside the image area. Released mouse, the mask showed as a rectangle, covering about two thirds of the left side of the image (as expected).

Clicked on the upper right button and moved it horizontally back to the desired location, as described previously, so the left edge was vertical, the top and bottom edges were horizontal, and the right edge was angled from upper left to lower right. All four corners of the bounding box remained outside the image area.

When I released the mouse, the, angled, right edge of the mask was correct, but the bottom portion of the green mask immediately disappeared (as if the horizontal bottom edge of the mask had been moved up into the image by about a tenth of the height of the image), even though the lower boundary line, and points, remained outside the image. Clicking OK, resulted in the finished image having a noticeable horizontal line between the two tonal differences in the bottom area of the image.

Tried this a couple times and the same thing occurred.

Hope my explanation was clear enough to understand.

Marv
Marpel
Posts: 692
Joined: September 13th, 2009, 3:19 pm
What is the make/model of your primary camera?: Nikon D810
Location: Port Coquitlam, British Columbia

Re: Composite with Polygon Mask

Post by Marpel »

Couple more comments:

It appears the area cut off at the bottom of the mask is somewhat related to the distance the bounding box, and control points, are outside the perimeter of the image. The farther out they are positioned, the more the bottom is cut off of the resulting mask. If the bounding lines/points are in complete alignment with the image edges, no mask seems to be cut off, but that is a bit difficult to precisely accomplish.

And I should also explain, the reason why I shrink the image a bit is, I find, when the image is at default size (actually two images side by side) it is a bit difficult to ensure the full image is masked, because the image title bar and zoom in/out/zoom to fit buttons block the placement point(s) of the upper right and left of the bounding box. Because the area below the image has ample space, it is easier to place lower control points.

Marv
jsachs
Posts: 4203
Joined: January 22nd, 2009, 11:03 pm

Re: Composite with Polygon Mask

Post by jsachs »

OK, I think I see it.
Jonathan Sachs
Digital Light & Color
jsachs
Posts: 4203
Joined: January 22nd, 2009, 11:03 pm

Re: Composite with Polygon Mask

Post by jsachs »

It looks like it was an overflow problem when working with large images. Should be fixed for the next release.
Jonathan Sachs
Digital Light & Color
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