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Advice for Night VFX Shoot

M

Mondo Ghulam

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Hello,

I hope this is the appropriate forum. I'm looking for some advice about what to expect from a camera / lens / lighting package for an up-coming night shoot that I'm vfx supervising.

We will be shooting Epic, likely with Zeiss Super Speeds. I'm very comfortable with my Scarlet + Canon lenses, so I'm confident that the camera / lens package for this shoot will greatly exceed my expectations. The 'wrinkle' is that the only light we'll have, is a 4K HMI Helium Balloon light which will double for the moon. Full moon will actually be 2 days before the shoot starts.

It's a lowish-budget short, scheduled for late October, NW of LA, in a low-density forest. One of my tasks is to make sure the plates can be tracked accurately in Syntheyes or equivalent for integration with CG.

I'm very comfortable with shooting plates for tracking in good or lowish light but have been told to expect low to no light. Aside from some tests, I have no experience of these particular conditions.

My concern with this shoot is that the light available may not permit the tracking of natural features within the plate. As a precaution, I'll be using LED markers to ensure we get trackable data, these of course will require painting out later. I'd like to use as few LED's as possible to minimise paint-outs.

Has anyone used these lights or had to track a plate having been shot in such conditions with EPIC? Any insight would be greatly appreciated.

Cheers,

-M
 
The only advice I can give is that even two days after full moon, you should be getting some appreciable moonlight. And contrary to popular belief, the moon is not necessarily directly above at midnight; for example two days ago the moon was at its apex around 3am. So you might want plan a bit for the moon.

GOOD LUCK!!
 
The small battery keyring ledlights are not allways that good as they tend to flare and change shape when camera moves. I done the mistake, figured I fixed it with dimming them down by putting on some gel.. that did not work to well as then there is no clear dot.
I worked with keyring lasers before, those work great if you put them so that they aim at a surface visible from the camera... of course you get some issues if there is a lot of smoke and stuff and you might want to make sure that it's not one of these kind of laser that can kill the sensor.
 
Björn,

How about using green glow in the dark tape to make some tracking points? They would have to be charged up every so often by shining a light on them, but that might work, no?

Or perhaps using glow sticks?
 
Thanks Peter & Bjorn,

This is good information to have. I'm still experimenting with LED's and will try the keyring lasers too - there's no smoke or anything like that anticipated for the shoot. How do you mount them?

Regarding LED keyrings, I've seen the directionality/glare too and have a work around for that. It gets a bit Heath Robinson mind ;) but works quite well. If you fit a plain ping-pong ball over the bulb it cuts a lot of glare & gives you a larger area to work with. It behaves more like a motion capture marker.

For distant markers - works just as a dot, but because of the increased surface area, you can also stick a triangle of tape over it and get 3 points to track. Depending on dof etc. and size in frame this can work for middle distances too. For close in I'd still like something smaller and the lasers sound perfect for that.

The ping pong ball cuts the light quite a bit, but you still get some caustic-like variance from the LED bulb itself and it's still bright. The way I got around that was to use Scotch Magic tape - the kind used for taping down animation paper:

http://www.chromacolour.co.uk/productdisplay.php?parent=Traditional 2D Animation&child=Magic Tape

It's a really great diffuser and almost entirely removes the variance - as well as stopping the light down further. You still have a seam from the ball, but depending on where you place the hole for the LED, you can use it or lose it.

I also opted for the submersible LEDs as they're water proof and have a twist-base that makes changing batteries/turning them off easy as well as sitting up nicely on a surface.

I'm hoping that the combination of HMI and fast lenses - and the Epic of course, give me what I need without too much marker madness.
 
Peter Moretti said:
Björn,

How about using green glow in the dark tape to make some tracking points? They would have to be charged up every so often by shining a light on them, but that might work, no?

Or perhaps using glow sticks?
Click to expand...

I'm going to try this too - great idea.
 
I would put the Lasers using clamps on a C-Stand somewhere off camera aiming them at a location the camera can see. This will prevent any worry about the sensor being hit by the laseer.
 
3M "retroreflective" tape is great at night (same stuff they use on runners gear for night runs)... can create a really bright circle with very even very little ambient light.
Might try Covering a ping pong ball with the stuff and it should glow from almost any light sources you are using... the finished spheres will look like the classic "animal eye" in the dark, and can get gaff taped to trees/rocks, or just laid on the ground.
Hope this helps!
-CK
 
Thats a good idea, I just worry that with using 3M reflective tape you'll end up with a flare / uneven glow, that will compromise the integrity of the track.
 
I'll give the scotchlite a try. I'm wondering if a small array of LEDs behind the camera might be enough to light up the tape, without affecting the overall lighting - should i run into problems with available light. For motion capture, it's a ring of near-IR LED's that produce an incredible amount of 'level' from the markers - which are basically scotchlite wrapped over a soft rubber ball.

With the laser mounting on a C-stand, it occurred to me that the tiniest bit of movement at the source, could cause a large shift in the dot's position which would interfere with the track. Only way to know is to test but with a few dozen people behind the camera, things can go 'bump' in the night.

I'm very keen to use something passive that doesn't spill too much light - so I have a bit of a shopping list now with Glowtec tape, Scotchlite and some lasers. If either of the passive approaches prove successful I'll post up some results and findings. The moon is a few days on the wane now so if I get a usable result in the next few days, I know the shoot will only improve on that result.

Many thanks for the advice!

-M
 
I use tiny glowsticks for this type of situation. Yellow to be exact. They're the same glo-sticks that fit inside of a golf ball. Used by golf enthusiasts playing at night.
Has worked really great for me, especially when close to camera, then I'll use standard size glo-sticks in the distant BG with some gaff tape to cover up any 'extra' light they emit.
 
I would just let the keyring laser lay around / gaffered up hidden for camera. Does not need much "install time" if you really want a good track you also bring your laser tape measure and measure the distance in between the dots created. Then you feed that into synth eyes and your track will be tons better.
 
If you end up using the small keychain lasers you could place them or hid them deep in the frame just a short distance in front of the target that way even if there was any haze or they caught any smoke/clouds/dust the line from the laser would be very short and you probably would not notice it as much as if you sourced it from out where the camera was.
My experience with low light and trying to use targets is if you use things like glowstick and defused light sources you end up polluting the surrounding areas possibly. And the source is never nice and crisp. Small red LED like on the back of a digital SLR works very well and doesn't bleed everywhere on the image if its a far enough away from the camera. Top and bottom of the frame if you can and there should always be at least 1 set in frame during the move.
Good luck.
 
I'm just waiting on all the various bits and pieces to arrive now and looking forward to trying them all out - my local park is going to be lit up like a Christmas tree while I test all of this out.

I'm really keen to see how the keyring-lasers work out, the ones I ordered have a range of 1 mile. In the location I'm not allowed to put anything on trees, I'm hopeful that lasers will simplify the setup enormously. Earlier in the thread someone mentioned about laser vs. sensor. We're shooting Epic, I'll be testing on Scarlet. My understanding of laser-damage to a sensor is that it happens only if the laser shines directly into the lens. Assuming no mirror-reflections, we should be risk-free with laser dots reflecting off of trees, rocks or even little paper targets I might place in the scene?

I always supply Syntheyes with some measurements from the scene and shoot a 'known' configuration of markers or measured features somewhere in the plate, to establish, scale & coordinate system / compass direction.

Most of the shots are farily contained area-wise and I think the lasers or glow tape might be adequate for those, for one shot, there is quite a bit of ground to cover and I can see a combination of all of the technicques being used for that shot.

Thanks everybody!

-M
 
Over the weekend a lot of stuff arrived. Thought I'd feedback some initial findings.

Laser key-rings.

These are awesome - thanks for the suggestion Bjorn!

In a test the point of light changes shape in interesting ways, but the tracker holds the centroid and in a quick test with modest settings, the dot was clearly visible at 20-25 in darkness. I've got 7 total and have still to try a full 3D solve with that, (syntheyes needs a minimum 7 trackers). If that works out I'll be getting more.

The lasers throw out a powerful dot and some exhibit a bit of scatter from the housing. So I'd be tempted to use them mid to far.

Glow tape:
Got some really good stuff from Glowtec. Pros - it lights up really well, Cons - doesn't hold the glow for long. 10 minutes before it settles into a very dim, pallid glow. It'd need re-charging before each shot. It'd probably be good for elements close to the camera as it's not too overpowering.

Scotch Tape:
I've found it impossible to purchase ScotchLite tape, here in the UK. The matte kind that's really bright with small amounts of light. Everywhere seems to sell a cheaper, gloss-coated version. It's okay but nothing like the matte finish type we'd use for mocap markers or seen on hi-vis vests.

LED + Golf Balls:
Working really well. I've run one for almost 30 hours and it's held luminance throughout. It's good for mid/far but the ball is too big close in - unless the marker is going to be covered by the CG element.

So my 'worst' case strategy will be to have lasers for far/verticals as I'm unable to place things on trees. LED's for the ground mid/far and for the elements up close, I'll try good old gaffer tape (fluorescent colour but not fluorescing).

Thanks
-M
 
Great thread! I have no expertise in this area, but am following the discussion with interest. Mondo, if it's possible, can you show us some behind the scenes shots of whatever solution(s) you end up going with for your actual shoot? It would be great to see some actual examples if I ever need to work on something similar.
 
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I know I'm coming to your thread late, but I would have suggested just using the LED's. I suppose if you cannot get one high enough, then a laser is an idea, but I worry about the mounting on a laser. A C-stand out on some dirt in the forrest with a laser pointing at a really far distance... that seems like trouble in the making as I can't imagine it not wobbling a bit. Someone on the crew steps and that tiny vibration wobbles it.

When I've used LED's for shoots, it's worked. I used too many and the hardest part was just roto'ing them all out. They definitely bled onto the surrounding area causing a little too much brightness even after we gaffer taped them a bunch. LED's come in different brightness and if you're doing something close, you can get away with the lighter brightness. Choose a color you could key out. It will not key that well, but maybe the reflective lighting could be reduced.

Remember the whole goal is to get spots at various planes. So spread them out - especially in the distance. you only need to go high if you aim up out of the ones that you have in view lower.
 
Hi Jaakko,

Yes absolutely. I still have to do a full exterior test here, I didn't have everything delivered by the weekend so I had to do some other tests instead. I'd be happy to share any bts of that too.

I will be taking many stills on this shoot partly to survey the set and also to help with tracking later. I'll post up a collection of them and an explanation of how it all worked.

Something that surprised me was that Syntheyes really 'liked' triangle on the ping pong ball, even when out of focus and it also liked the laser 'dot' a lot, even though it changed shape from dot / horizontal / vertical every few frames.

Something I noticed with the laser is the way it responds to different coloured material. Shine it on white and it's huge, shine on black and it becomes a much smaller but still tightly defined dot, so on a dark target it *might* be good for close up elements too.

-M
 
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