Filter avail to remove raindrops on lens?

Christian de Godzinsky wrote on 9/16/2008, 1:12 PM

Hi,

I'm editing a skydiving video. The guy that filmed the jump with his "helmet-cam" did a fine job. However, it was a rainy day and there are raindrops on the surface of his wide-angle lens, that shows up pretty well in the video, and are quite disturbing.

I wonder if there exists a filter some kind (Vegas or non-Vegas) that would at least make the drops less visible, without blurring the skydivers too much. Most of the drops stays stationary (!) for the majority of the time! I suppose it would be possible to at least filter them out from the sky portion where they disturb at most. The video is however quite "shaky", so I do not want to mask it frame by fame...

I wondered - you Spot being a pro in this field - would you have some wise words - other than do a re-shoot - that is not an option. OR are you just skydiving during good weather ;) ?
cheers,

Christian

Comments

John_Cline wrote on 9/16/2008, 1:47 PM

Raindrops on the lens sounds like it would be a difficult to remove as wind noise on an audio track. Basically, the raindrops are acting like a bunch of little lenses themselves, I suppose that a filter could be written that could perform the inverse of the optical characteristics of the raindrops, but it would be hugely difficult and impractical. I suppose with a LOT of work, this might be able to be accomplished in After Effects using an existing third-party filter. Even though the drops stay stationary, they are probably changing size due to the wind and their optical properties don't remain constant.

Personally, I think you're just going to have to live with it. Maybe you can explain to the audience in the narration that it was raining and people will just accept the rain on the lens as part of the difficult nature of skydiving.

JJKizak wrote on 9/16/2008, 1:55 PM

Or add a lot more rain drops as an effect.
JJK

johnmeyer wrote on 9/16/2008, 4:31 PM

This is easy to fix, and with free software. I just did about twenty hours in Vegas the past few days.

You use Delogo, a filter for Virtualdub.

You then use Wax, a free plugin for Vegas.

You configure Wax outside of Vegas and make sure the "Use Dummy Host ..." is checked. You need to do this to get it to work with modern versions of Vegas.

You do a frame grab of one frame where the spots on the lens are easiest to see (i.e., really obnoxious). You bring this into your photo editing program and select pure red, with no feathering (pure red is 255 in the red channel and 0 in all the others). Paint over each spot, making sure to go a few pixels beyond what is needed to cover (i.e., make the spot a little too big). Save that.

Then, in Vegas you add Wax as an fX to the media or the event. In Wax, scroll horizontally in the center of the dialog until you find VirtualDub. When you installed Wax, you were asked to provide a plugin folder (you can also do this from the preferences dialog mentioned above). This is where you put the Delogo.vdf file. You then load the mask file you created, check or uncheck the interlaced setting, depending on what sort of footage you are repairing, and that should be all you need to do.

Oh, on my computer, once I have added Wax as an fX, the dialog appears and then immediately disappears. Just click on the event (not on the fX button, or pan/crop button, but just in the middle of the event). The dialog will then pop up. Also, if you save and later re-open the project, you will have to re-configure all the Wax/Delogo settings -- they are not remembered between sessions.

So, a few rough edges, but the results can be quite excellent.

Oh, read the instructions for Delogo. In addition to the simple repair I just mentioned, it also is designed to remove semi-transparent "bugs" from video you capture from commercial television. This works REALLY well, and is actually probably closer to what you want to do. However, I would suggest that you create the mask using Delogo inside of VirtualDub. Once created, you can then import and use that mask inside of Vegas as described above.

This may sound complicated, but it takes me only about two minutes to set up.

If you want to post a few seconds of the footage (as long as it isn't AVCHD, which I cannot handle), I'll be glad to fix it and post the results. I think you'll be quite happy with it.

PeterWright wrote on 9/16/2008, 5:50 PM

> "Paint over each spot, making sure to go a few pixels beyond what is needed ..."

I tried that with a pic from a current photo contest, and one of the skydivers disappeared!

- sorry, couldn't resist ; )

Christian de Godzinsky wrote on 9/17/2008, 11:38 AM

Hi,

JohnM, thank's for the long but detailed description. If I have time I will give it a try.

My Vista 64 PC went totally crazy after installing both 8.0c and 8.1, and the latest Windows updates.. Both applications just quits unexpectedly without a trace. The whole PC became unstable, haning, leaving from time to time the cursor immobilized. I tried everything I could imagine, and now I'm (finally) reinstalling Vista 64 + all the sw. Goosh what a nightmare!!! I tried even system restore(s) with no help...

So - my deadline is in danger because the reinstall of everything. If i can get more time for this project, then I will give it a try.

And as you said, there's one spot that I don't want to erase ;)

Christian