Tilt (Rotation) Correction Problems

wcoxe1 wrote on 10/23/2002, 9:33 PM
Nothing is quite so frustrating as an otherwise perfect shot that is tilted just a little to the right or left. Makes the water in glasses look like it should pour out. That sort of thing.

I thought for a while that VV could fix it using Pan/Tilt-Rotate. However, in some shots, using as little as ONE degree of rotation causes all kinds of objectionable Moire' effects, or worse, outright pixelation. BIG pixelation in some cases, especially in moving objects. And, just TRY 6 degrees. Ha! Horrible.

Anyone have any tips for proper handling of this problem, other than don't tilt the camcorder? Please?

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Camcorder
Sony: DCR-TRV20

Vegas Video
Version 3.0c Build 138

Operating System
Platform: Windows 2000
Version: 5.00.2195 (Service Pack 2)
Language: English
System Locale: English
User Locale: English

Processor
Speed: 1GHz
Class: Pentium III
Identifier: GenuineIntel
Number of processors: 1
MMX available: Yes
SSE available: Yes
SSE2 available: No

Display
Primary: 1024x768x32

Video Adapter
Name: nVidea RIVA TNT2 Model 64
Memory: 16MB
Bios: 2.05.1704

Memory
Physical memory: 261.3 MB
Paging memory available: 631.7 MB
Virtual memory possible: 2,097.0 MB

External Monitor:
Sony PVM 1353MD

External Monitor fed by:
Firewire card to DataVideo DAC-2;
then, Component VUY to Sony PVD 1353MD

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Comments

Chienworks wrote on 10/24/2002, 2:24 AM
Try setting the video rendering quality to "Best". This will use a slightly softer resampling algorithm which might hide the jaggies and help prevent moire patters. A tiny touch of Gaussian blur might help too.
wcoxe1 wrote on 10/24/2002, 10:24 AM
I'll try the tiny touch of G Blur. I already have it on "Best." Hope this works. Some of the pixelation looks like I was deliberately hiding people's identity. That bad. And diagonal lines, well, horrible isn't strong enough. They pixelate and seem to jump in and out of the picture.
John_Cline wrote on 10/24/2002, 2:34 PM
The artifacts you describe are caused by trying to rotate an interlaced image. I have sucessfully done it a few times where I separated each field in a 29.97fps 720x480 video into individual frames at twice the frame rate. This will result in a series of 720x240 images. I then rotated the images and re-interlaced the images back into a 720x480 29.97fps video. I had to use a few different programs to do the field to frame conversions and the rotation, but it ended up working quite well.

John
SonyDennis wrote on 10/24/2002, 3:45 PM
Are you sure your source footage is set to "interlaced"? If so, Vegas will apply motion (including rotation) to individual fields rather than the whole frame (which would look terrible). If you have interlaced footage set to progressive, the result would have moire and other effects.
///d@
FadeToBlack wrote on 10/24/2002, 4:55 PM
magicman wrote on 10/24/2002, 6:13 PM
It's not mentioned so I'll ask. Is what you are experiencing observed after you have rendered? Or is it just during preview. Also, are you viewing this on you computer or TV? If you haven't rendered...try it, and see if you have the same ill effects.
wcoxe1 wrote on 10/24/2002, 8:24 PM
NONE of the artifacts show up during preview on computer or on an external Sony PDV 1353MD Medical production monitor that has recently been calibrated and I am using it according to directions. Color is excellent. I have it set for component input.

However, AFTER rendering, and during playback on TV or on the camcorder screen, the artifacts are VERY pronounced. It is NOT visible on the computer or external monitor before OR after rendering.

I checked. It is set to interlaced.
SonyEPM wrote on 10/25/2002, 8:28 AM
Try setting the preview quality to "best" and "display at project size"- then check the external monitor with this hi-rez preview setting- do you see the problem?

wcoxe1 wrote on 10/25/2002, 9:47 AM
When I switch to "Best Preview" and set to to display "At Project Size," the pixelation and moire' are quite pronounced. In fact, it is worse than I had realized, on those areas of rotation. I guess some of it is small and not noticed on TV and the external monitor, but when it is bad, it is REALLY bad, now.
wcoxe1 wrote on 10/26/2002, 8:06 PM
I just finished rendering after taking a bit of advice that, to me, seemed backwards.

I had an image breaking up, lots of moire and pixelation caused, apparently, by using rotation. So, I applied a tiny bit of Gaussian Blur, as recommended by Chien. As small as I could possibly apply, .001, each. And, you know what? It WORKED. By making it ever so slightly blurry it cleared up the break up, made it sharper, in effect. It was remarkable how much it was improved, and the tiny bit of blur was not noticable at all.

If it works, do it, even if it seems backwards.

Thanks to all who helped and contributed. Much appreciated.
SonyEPM wrote on 10/28/2002, 9:09 AM
you might try the "reduce interlace flicker" event switch (next time)
wcoxe1 wrote on 10/31/2002, 10:20 AM
Although the suggestions above seemed to "cure" the problem, I didn't learn the actual CAUSE of the problem until later, so here it is. Maybe.

I discussed this matter during a converstation with drdropout about an entirely different problem (Miscaclulation of PTT segments). He and I concluded that it is likely the use of both Sharpen and Rotation in the same event caused, or at least accented the pixelation problem and moire effects. I, not being any kind of expert on video logic, was thinking that, if anything, sharpen should HELP. Turns out, after investigating the main problem areas, that EVERY one of them had a very tiny amount (.001) Sharpen and Rotation, Ah HA!.

I went back and prerendered a few events WITHOUT Sharpen. The problem is not showing up, now. I have yet to do a full render of the project (I obviously am a slow learner, and used Sharpen all over the place) because I have many places to remove Sharpen. There is no global place, like View/Edit Details, where I can get at all of them at once. I will try to get back and post the results of the global removal of Sharpen in places where there is Rotation at a later date.

Thanks, everyone, for your contribuations.
wcoxe1 wrote on 11/2/2002, 10:43 PM
I just finished the complete render of my whole project, WITHOUT all the Sharpens. I removed them from every event that had even the smallest amount of rotation (tilt).

The moire' and pixelation has completely disappeared. I removed the Gaussian Blur, mentioned above, also, since it was no longer needed. It seems that not only was I able to cure the problem, but we finally diagnosed the cause of the problem well. I will never again try to sharpen a picture, even a tiny amount, if there is ANY rotation, what-so-ever.

Thanks to all who contributed. Much appreciated.