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blended screen trouble

jeff goodin

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I am having an issue getting my projectors in the desired position while using the blended screen tool. I would like to split the screen in two halves to shorten my throw distance. When I insert the projectors, both cover the full screen and I cannot figure out how to change the setting.

To be clear, I have two projectors covering one screen. I would like each one to cover 50% of the screen but when I insert the projectors, both cover 100% of the screen and I cannot figure out how to adjust the setting.

Deadline Monday, help please.


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I thought this would have been an easy task but like you I am having trouble.

The only thought that I am having is that Vectorworks have not allowed for a blended screen to contain side by side projectors that do not cover the screen entirely, ie 50/50. there for the only valid workaround that I have found is to insert two regular screens 6' x 21' with separate projectors and if required map the coverage area with a screen of the overall size, see attached.

If anyone had found options to change the side by side blended screen which is a 50/50 line up I'd be interested to know.


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Jeff -

A few things:

1) Blended Screen calculates projector spacing based on 2 things: Screen Size (height and width) and Projector Aspect (4x3, 19x9, etc.). A combination of Screen Height and Projector Aspect determine a single projected Area Width. (For your example, the single-area width for a 12'-high screen and 4x3 projectors is 16' wide.).

2) At this time, the tool only places far end projectors so that their far left or right ends meet the far left or right edges of the screen. The placements for the interspersed projectors (if any) is calculated so that the spacing and overlaop are even. The tool will not allow for fewer projected areas than it will take to fill the screen. (For your example, the fewest is 2 areas, with an overlap of 11'. Different Projector Aspects will produce different area overlaps.)

3) For determining spacing/overlap, the lens spec. is irrelevant, regarding Blended Screen and/or VS4-Blended Screen. That simply changes the projection depth.

Probably more info than you wanted. I'm just wanting to make sure you're understanding the underlying logic.

So...I'm curious as to what your parameter settings are that are producing 100% overlap.

Also, please let me know if there is fuctionality that you're needing that is missing. For example, are you needing the tool to allow for End Overshoot (or, whatever you might call it)?

Regards -

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Jeff, I wish I found this post before your deadline. Hope you made it.

Using the blended screen tool in Spotlight 2010, I was able to make a 12'x21' using two 4:3 projectors. I found that the "insert projectors" button acts more like a refresh button while the "Update" button refreshes screen features. Area Horiz Count is your friend. Update that value and hit Insert Projectors.

Single 1.38 lens on a native 16:9 is 29'-39'

Dual Blended 1.45 on a native 4:3 is 23'-30'

[based on Barco TLD 1.45-1.85 (4:3) / 1.39-1.87 (16:9)]

Your overlap is 11' and you've got 704 pixels of blend. You can save about 9' vs a single 16:9 native projector.

Any shorter of lenses and the blend can become troublesome. Blending 0.8's and .73's can be done but it is time consuming. Particularly useful if you need to task a projectionist with a long and arduous job.



Edited by GBarrett
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Thanks Andrew and Greg for the explanations!

My understanding now is that 12'x21' is a native 16:9 resolution, so when I assigned a projector with a 16:9 format it filled the entire screen whereas when I switched the projection format to 4:3, which would not align with a 16:9 screen, the tool knew that it would have to add a projector to fill the entire screen.

Does this sound right to you guys?


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Jeff -

12'x21' isn't exactly 16:9, but close enough that a single 16:9 projector will fill the screen so, yes, you are correct.

Regarding the difference between "Insert Projectors" and "Update:"

- If no projectors are present, "Insert Projectors" will insert them, using the parameters defined in the Screen's OIP. If projectors are present, clicking that button will delete them and reinsert them, resetting any text settings.

- "Update" will refresh both the screen and existing projectors w/o losing text settings. Though it won't account for area count changes, it is good for things like changing lens spec.

Regards -

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Hey Andrew, I just thought of a good add-on. A "Show Throw Distance" option would be helpful. It would report the distance from lens to screen. I'm always drawing in that distance anyways.

Jeff, you are on the right track. Gotta keep in mind that changing a 4:3 projector to wide mode doesn't help you at all. The proj needs to have a native 16:9 chip in order to squeeze the additional width without needing additional throw. Asking a 4:3 native chip to fill a 12'x21 really means you are asking it to shoot at 15.75'x21' in wide mode.


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