Re: Questions/problems with point params in FCP
Re: Questions/problems with point params in FCP
- Subject: Re: Questions/problems with point params in FCP
- From: Joe Stern <email@hidden>
- Date: Thu, 03 Apr 2008 23:15:40 -0400
- Thread-topic: Questions/problems with point params in FCP
Title: Re: Questions/problems with point params in FCP
I have seen this behavior when using the garbage matte effect, especially on oversized pictures.
Joe Stern
CNN Post Production
Atlanta
On 4/3/08 3:56 PM, "Paul Schneider" <email@hidden> wrote:
Hi, Pete,
this looks like a bug in Final Cut's crosshair display. The point control is relative to the layer, not the sequence; in other words, (0, 0) should be in the upper left corner of the layer, regardless of where you move the layer. The "Motion Tab" transformation is done *after* the filters.
Our built-in effects work this way, too - you can see it with Target or Fisheye. The effects are interpreting the point values correctly, but the app is drawing the crosshair in the wrong place.
So, you don't need to adjust your values by any magic number - we just need to fix our crosshair drawing.
- Paul
On Apr 2, 2008, at 7:31 PM, Peter Litwinowicz wrote:
Okay,
Here goes: first the header files say point params are designated from the lower left. Not true in FCP, points are specified from upper-left, with Y going down the image. Can someone fix the docs (not sure what Motion does... Haven’t tested). Okay, that one was easy to figure out.
Here’s another issue:
Let’s say I place a point in the upper left corner of the image. I get back (x,y) == (0,0). Which is what I expect. See picture below of what FCP draws when I select the point param in my filter. A red “+” is drawn at (0,0). Cool.
<image.jpg>
Now let’s say I move the sequence’s center, as seen below.
<image.jpg>
Note the red “+” does not move with the image. However when I retrieve the point value it is still (0,0). However, if I were to use (0,0) as the point’s value, that pixel in the image (0,0), is not where the red “+” is.
Paul (or someone on the FCP team) can you give me the set of calls I need to make to transform the point so that I can find the corresponding pixel in the image where the red “+” would be? I need this so the user can align where FCP draws the point is and the corresponding (sub)pixel position of that point in the image. I presume there is some combination of anchor and center points and scaling and rotation, but it would be nice if I didn’t have to reverse engineer it :-)
Pete
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