A Thousand Words...HV20/Brevis short.

Daniel Lipats · December 24th, 2007, 02:44 AM

Quote:

Originally Posted by John Papadopoulos

Daniel,

How is the second camera used to remove the shutter distortion? I haven't seen that.

Deshaker has parameters that allow to control the ammount of correction. It's not much if you loose 5 or 7% to get extra stability. With a fast shutter it can be artifact free in other aspects. With CCD and global shutter cmos you have an option at least.

That got me thinking, its been a while. I think I originally was introduced to the idea here:
http://wiki.elphel.com/index.php?tit...n_Compensation

And may have seen it referenced elsewhere. There are other methods used to reduce the rolling shutter effect. I think SI2k shoots at twice the frame rate and drops every other frame to help minimize distortions but I have not had a chance to test this for myself.

Some people don't seem to be bothered by it at all. When I watched Peter Jacksons trailer for "Crossing the Line" shot with RED I noticed a lot of distortions. Others that I played it for didn't mention a thing about it, they thought I was crazy. The newer footage I have watched from RED I have a hard time finding distortions.

The percent required to stabilize a shot will always be relative to how bad the footage is. 7% is kind of suddle, enough for an unstable dolly but In my case I was attempting to stabilize a hand held sequence shot by what seemed like a crippled camera operator. I tried using deshaker, combustion, and eventually steadymove pro. I had very poor results with each and ended up doing it by hand. Even after stabilizing a single shot, the loss in resolution can show as the options come down to cropping the rest of the film or upres the corrected shaky sequence. Nonetheless, software such as deshaker have their uses and are an important asset.

John Papadopoulos · December 24th, 2007, 03:03 AM

Removing rolling shutter will not be easy. Try to step through the sirlatelot clip and see how complex it actually is. Normal shake with horizontal and vertical distortion on top.

John Papadopoulos · December 24th, 2007, 03:09 AM

Quote:

Originally Posted by Daniel Lipats

That got me thinking, its been a while. I think I originally was introduced to the idea here:
http://wiki.elphel.com/index.php?tit...n_Compensation

Some people don't seem to be bothered by it at all. When I watched Peter Jacksons trailer for "Crossing the Line" shot with RED I noticed a lot of distortions. Others that I played it for didn't mention a thing about it, they thought I was crazy. The newer footage I have watched from RED I have a hard time finding distortions.

Where would the distortions come from on Red? It's global shutter, isn't it?

EDIT: I thought your link was a generic reference to rolling shutter. So the RED is actually rolling shutter. That's news for me. So, no flash photography wedding shoots with it:) So, the Red will not look very good in a club with a strobe or red carpet scenes or effects with flashes. Sounds like a very serious limitation. There are $200 camcorders that do not have a problem with these shots.

http://www.redhax.net/wiki/Understan...tter_Artifacts

Daniel Lipats · December 24th, 2007, 03:53 AM

Maybe, but comparing RED to a $200 camcorder is just silly.

I have watched quite a number of shorts and tests shot with the RED and honestly have not noticed any distortions on anything shot on a production model camera. It captures amazing footage and in my opinion is the benchmark for independent, and industry wide cinema (considering the price).

It is nice to see some competition entering and I look forward to see things develop. Competition is the driving force of technology and we all benefit from it.

Noah Yuan-Vogel · December 24th, 2007, 09:07 AM

In my opinion, the distortions in this video are partly from rolling shutter artifacts. I have done digital stabilization on dolly/handheld shots with both ccd and rollingshutter cmos. the skew/stretch/compress distortions are from the rolling shutter, but the blur distortions are from stabilizing bumps shot with a normal 1/48th sec shutter. both types of distortion are noticeable and together even more noticeable, but certainly a nice looking short film otherwise.

distortions throughout crossing the line (peter jackson's RED short)? i saw it in 4k at nab and was watching quite carefully for various artifacts and didnt see much besides the one really noisy shot. ive seen a lot of mention of skew/distortion artifacts but if they were there they werent nearly as noticeable as anything ive seen on the hv20 or si2k. then again maybe people are just more careful with their REDs, and ive never used one. ive only seen skew on the si2k when i was playing with it briefly at nab panning it back and forth really fast.

i dont necessarily think its silly to compare red to cheap camcorders. i mean red is supposed to be no compromises but to think you might be better off shooting a runway fashion show with a $200 camcorder than RED since red will be all half-frames all the time. then again if they support windowed SD resolutions with ridiculously fast framerates or at least the same ridiculously fast pixelrate, maybe then at least people shooting things normally hazardous for rolling shutters would have options. or maybe work in a mechanical shutter option.

John Papadopoulos · December 24th, 2007, 11:34 AM

I think those who buy Red could make a Canon HV20 look excellent:) They are usually quite experienced, the setups are very professional, lighting is good, etc.

Daniel Lipats · December 24th, 2007, 11:38 AM

Yeah, personally I noticed the distortions in "Crossing the Line" right away. The skew was there with panning cameras or fast moving objects such as wheels. Did not even have to look for it. Im guessing it was worse in that film because it was shot with a prototype camera. Either people really are more careful or the production model is improved.

What I meant by my comment about comparing RED to a camcorder is that I believe they are built for two completely different reasons, and markets. As far as I know RED is designed for cinema and controlled shooting situations. Furthermore, it is unclear how RED would perform in situations such as the ones mentioned. I have yet to see such an example.

As I mentioned earlier, just because a camera has a CMOS chip does not make it a poor tool. Its just knowing how to use it. Even with the rolling shutter distortions and other limitations of CMOS, carefully shot films with the hv20, RED, V1U, and others look outstanding.

December 24th, 2007, 03:03 AM	#17
John Papadopoulos Major Player Join Date: Nov 2007 Location: Athens Greece Posts: 336	Removing rolling shutter will not be easy. Try to step through the sirlatelot clip and see how complex it actually is. Normal shake with horizontal and vertical distortion on top.

December 24th, 2007, 03:53 AM	#19
Daniel Lipats Major Player Join Date: Feb 2006 Posts: 260	Maybe, but comparing RED to a $200 camcorder is just silly. I have watched quite a number of shorts and tests shot with the RED and honestly have not noticed any distortions on anything shot on a production model camera. It captures amazing footage and in my opinion is the benchmark for independent, and industry wide cinema (considering the price). It is nice to see some competition entering and I look forward to see things develop. Competition is the driving force of technology and we all benefit from it.

December 24th, 2007, 09:07 AM	#20
Noah Yuan-Vogel Major Player Join Date: Dec 2004 Location: New York City Posts: 613	In my opinion, the distortions in this video are partly from rolling shutter artifacts. I have done digital stabilization on dolly/handheld shots with both ccd and rollingshutter cmos. the skew/stretch/compress distortions are from the rolling shutter, but the blur distortions are from stabilizing bumps shot with a normal 1/48th sec shutter. both types of distortion are noticeable and together even more noticeable, but certainly a nice looking short film otherwise. distortions throughout crossing the line (peter jackson's RED short)? i saw it in 4k at nab and was watching quite carefully for various artifacts and didnt see much besides the one really noisy shot. ive seen a lot of mention of skew/distortion artifacts but if they were there they werent nearly as noticeable as anything ive seen on the hv20 or si2k. then again maybe people are just more careful with their REDs, and ive never used one. ive only seen skew on the si2k when i was playing with it briefly at nab panning it back and forth really fast. i dont necessarily think its silly to compare red to cheap camcorders. i mean red is supposed to be no compromises but to think you might be better off shooting a runway fashion show with a $200 camcorder than RED since red will be all half-frames all the time. then again if they support windowed SD resolutions with ridiculously fast framerates or at least the same ridiculously fast pixelrate, maybe then at least people shooting things normally hazardous for rolling shutters would have options. or maybe work in a mechanical shutter option.

December 24th, 2007, 11:34 AM	#21
John Papadopoulos Major Player Join Date: Nov 2007 Location: Athens Greece Posts: 336	I think those who buy Red could make a Canon HV20 look excellent:) They are usually quite experienced, the setups are very professional, lighting is good, etc.

December 24th, 2007, 11:38 AM	#22
Daniel Lipats Major Player Join Date: Feb 2006 Posts: 260	Yeah, personally I noticed the distortions in "Crossing the Line" right away. The skew was there with panning cameras or fast moving objects such as wheels. Did not even have to look for it. Im guessing it was worse in that film because it was shot with a prototype camera. Either people really are more careful or the production model is improved. What I meant by my comment about comparing RED to a camcorder is that I believe they are built for two completely different reasons, and markets. As far as I know RED is designed for cinema and controlled shooting situations. Furthermore, it is unclear how RED would perform in situations such as the ones mentioned. I have yet to see such an example. As I mentioned earlier, just because a camera has a CMOS chip does not make it a poor tool. Its just knowing how to use it. Even with the rolling shutter distortions and other limitations of CMOS, carefully shot films with the hv20, RED, V1U, and others look outstanding.