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ASPN
09-03-2010, 09:48 AM
Hey everyone,

I was doing some brainstorming last night about how to go about creating a LiveSet that would essentially put highlighted Line of Scrimmage and First Down lines on the screen that are similar to what we see on major broadcast tv. Has anyone been able to come up with a way to do it?

-Tim

luis.ayuso
11-11-2010, 02:26 PM
We had considered the idea when we were streaming live high school football, but in the tricaster, your best bet is an outside system that could get a copy of the feed used, and write over that, and play it back through a channel. like they do on television, you could just chroma a bar externally to the grass and feed it on the last input available.

Dexter2999
11-11-2010, 02:33 PM
I read somewhere once that the system you see them do that with takes like 12 people and computers to do that one effect. Simple keying is one thing but that line is in effect being matted by the players so as to appear under/behind them. Which is quite a feat especially when you see them do it for a team with green jerseys.

That is nowhere near a simple trick. At first glance it doesn't look like much but there really is more to it than meets the eye.

Paul Lara
11-11-2010, 03:09 PM
Just to give you an idea what the networks are doing to accomplish that, they use 3 Frost systems running together to accomplish that effect. Piece of cake for anyone with an extra $300,000 ;)

SBowie
11-11-2010, 03:37 PM
Automation is expensive, especially in 3D - but a simple telestrator solution would be just as satisfactory (and more so) for lots of purposes.

ZachSchuster
11-11-2010, 10:41 PM
I was actually going to ask about this as a potential Newtek product. What all goes in to it is far, far above my understanding, but could something be possible that works along the same lines of 3D tracking software that is used in moving green screen shots? Something like this:

A Newtek system with multiple camera inputs and outputs (or maybe just one in and out if processing speed will not permit multiple feeds). Using technology from Lightwave, the user interface allows the operator to program markers on a virtual field by aligning the various hash marks on the field (I believe this is similar to how the big systems do it, but I could be wrong). Theoretically, if the hash marks are aligned properly, when the camera moves or zooms, the software will track the movement of the hash marks and move the virtual field with it. The green of the field (or blue like my alma mater) gets keyed out. Fading in the line of scrimmage and first down would be the easy part. There would probably be issues with green jerseys, but I've heard great things about the keying effects of the XD850.

Knowing the distance from the camera to each hash mark would be important for proper virtualization of the field. The system would include some sort of portable infrared trannscievers. You would need a third man at the hash mark you want to program with one of the units, and the other with the camera operator. A signal is sent from the camera unit to the guy on the field, and then sent back. The system would calculate the reflection time to determine distance. (There are probably other ways of doing this, I'm just thinking out loud.) Or you could use a long piece of string tied to the camera tripod. :D

The more hash marks in the system the better the tracking, especially when zooming in. And you would have to do this for each and every camera you intend to incorporate. That could mean a lot of setup and tweaking, and if someone tells you to move your camera over, even as much as a few inches, the entire camera needs to be recalibrated.

Yes, I am making this far simpler than it probably is. Can anyone from Newtek comment as to the feasibility of this type of product (regardless of my suggestion)?

I'm seeing two great products from Newtek. One dealing with live video production and the other dealing with 3D modelling. These might be two important ingredients to a killer new product.

And yes, I would be more than willing to beta test. Beta testers get a free model once it goes in to production, right? :deal:

Dexter2999
11-11-2010, 11:51 PM
That type of computing power for a real time effect would take van load of computers and "cloud computing" to share the processing.

With a special camera setup maybe? Have a prism split the view of the line of scrimage to a standard camera and a thermal camera. Use the thermal camera feed as a live matt feed. Which allows the matted feed to be put over the top of the keyed line indicating the first down.

Just spitballing.

Dunno.

Jim_C
11-12-2010, 05:03 AM
The Technology

One of the quirkier aspects of computer-generated video effects is the vast amount of effort it takes to do seemingly simple things. The most basic concepts can sometimes take a gigantic amount of effort to implement (see How Centropolis FX Creates Visual Effects and How Industrial Light & Magic Works for interesting background).

Painting a virtual first-down line on a football field is an excellent example of this process; the concept of painting a first-down line across the field on people's TV screens certainly sounds simple. As it turns out, implementing this is incredibly complex. It takes a tractor-trailer rig of equipment, including eight computers and at least four people, to accomplish this task

Here are some of the problems that must be solved in order for this system to work:

* The system has to know the orientation of the field with respect to the camera so that it can paint the first-down line with the correct perspective from that camera's point of view.
* The system has to know, in that same perspective framework, exactly where every yard line is.
* Given that the cameraperson can move the camera, the system has to be able to sense the camera's movement (tilt, pan, zoom, focus) and understand the perspective change that results from that movement.
* Given that the camera can pan while viewing the field, the system has to be able to recalculate the perspective at a rate of 30 frames per second as the camera moves.
* A football field is not flat -- it crests very gently in the middle to help rainwater run off. So the line calculated by the system has to appropriately follow the curve of the field.
* A football game is filmed by multiple cameras at different places in the stadium, so the system has to do all of this work for several cameras.
* The system has to be able to sense when players, referees or the ball crosses the first-down line so it does not paint the line right on top of them.
* The system also has to be aware of superimposed graphics that the network might overlay on the scene.

A key piece of hardware used in the system is a special camera mount that holds the television cameras. This mount encodes all of the camera's movement (such as tilt, pan, zoom and focus). The data the mount produces helps the computers understand exactly what each camera is doing in real *Another key piece is a computerized 3-D model of the field. The computers know exactly where the cameras are located in the 3-D model and can orient the virtual first-down line on the field accordingly. The model also accounts for things like the crest of the field and the location of the yard lines on the field.

Color palettes are also critical to the system. The computers must be able to distinguish between grass, on which the line should be painted, and everything else (players, referees, the ball, etc.), on which it should not. Color palettes solve this problem. You can see the palettes at work in this frame:

The player does not have the line painted over his jersey because of the color palettes.

All counted, there are eight computers used in the system:

* Four SGI computers
* One PC
* Three special computers used in conjunction with the television cameras

These special computers' sole task is to record aspects of each camera's movement 30 times per second from the camera mount, and then send that data back to the production truck for analysis and use.

Drawing the Line

In order to determine where the line should go, a central computer utilizes several pieces of information:

* The virtual field modeled from measurements of the actual field (taken before the game), and the data from the camera mounts showing each camera's range of view
* The raw video feed from the camera that's currently on-air (determined by a separate computer in the Sportvision production truck)
* Two distinct color palettes, one representing the on-field colors that should be changed to yellow to represent the first down line, and another representing colors that should not be changed (like those in the players' and officials' uniforms -- this allows a player to appear to "obscure" the line, making the line appear as if it were really painted on the field).

Once the computer determines exactly which pixels should be colored yellow, this information, along with the raw video feed of the tallied (on-air) camera, is sent to a computer that draws the yellow line 60 times per second. The line is then sent to a linear keyer to superimpose the yellow line onto the program video. Since it takes time for all this to occur, the program video is sent through several frame delays so that the generated yellow line and delayed program video can be synchronized and turned into what you see on your TV screen.

On game day, it takes four people to run the system:

* A spotter and an operator work together to manually input the correct yard line into the system. The spotter is in the press box and the operator is in the production truck physically keying in the correct number.
* Two other Sportvision operators are on hand to make any adjustments or corrections necessary during the game. These adjustments might include adding colors to the color palettes due to changing field conditions, such as snow or mud.

Altogether, the process of creating a first down line for viewers at home is far from simple. Any football fan watching at home would tell you, however, that it's well worth the effort.

http://entertainment.howstuffworks.com/first-down-line.htm

SBowie
11-12-2010, 06:22 AM
Simpler but still quite useful solutions can be contrived by eliminating some of the requirements.

For example, if the application is restricted to a few fixed cameras, a whole lot of expensive tech is no longer required. Game fields are generally simple rectangles, and it wouldn't take much rocket science to map custom lines to a rectangular shape, then warp and translate the entire overlay to fit a given camera's perspective. Having removed the requirement to do any tracking, most of what remains is just keying (which, mind you, is not trivial) and display control.

That said, I still think that for a LOT of purposes, you'd get just as much real utility (if slightly less glamour) by forgetting automation and using telestrator tech, which is much less demanding because it relies on the very capable (and more or less free) human brain for most of the calculations.

Jim_C
11-12-2010, 07:30 AM
Simpler but still quite useful solutions can be contrived by eliminating some of the requirements.

For example, if the application is restricted to a few fixed cameras, a whole lot of expensive tech is no longer required.


With fixed cameras you might also be able to premake 98 overlays for every yard mark and have them in a bin. Name them somehow for easy finding.

Then depending on what marker the ball is placed at , just choose that overlay.

I guess there are times when the ball isn't placed right on a yard line, but it would be pretty close.

SBowie
11-12-2010, 07:59 AM
Sure. On a VT, you could do this now quite easily using Aura.

You'd start by simply creating the graphic overlay series as individual layers or frames (pretty easy to do, I've even got a 'grid' macro to help), and applying a 4 corner warp to them to match the perspective for a given camera angle (it would take mere moments to make this adjustment to all images).

Then you could just jump to a frame (or layer) or hide the overlay as required. Along with that, you'd get drawing tools for telestrator use. If the overlay was - say - 40% transparent, you could probably forget the idea keying to let the players show through. Low tech can be good tech ...

Jim_C
11-12-2010, 08:14 AM
Yea telestrating using Aura and VT is a super powerful feature with a big WOW factor that I bet not near enough people take advantage of. Or even know it's there.

Although I wasn't even thinking that deeply and was just picturing 98 separate pngs in the Tricaster DDR DSK. Balls on the 32 yard line, click 32Home and overlay the yard line graphic..

SBowie
11-12-2010, 08:38 AM
That's a nice quick and dirty solution, Jim. The graphics would have to be 'pre-warped', but that's not huge. I think I'd still use partial transparency to add a little something to the mix.