UD100 User Guide Document: UD100-3
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4. Preparation for Edge Blending
4.1. Determine source signal resolution
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The image size and watching distance are two major factors to determine source signal resolution
and number of the projectors.
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If the screen size is 20m and the watching distance is 5m, the signal pixel pitch should be around
5mm (around 1mm for 1 meter watching distance). The system resolution is about
20m/5mm=4000. It means the system resolution should be around 4000 pixels in width and the
vertical resolution should follow the projector native resolution. If WUXGA projector is used, the
ideal system vertical resolution is 1200.
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After determine the system resolution, please make sure all the equipment in the signal pipe line
should be able to support this resolution or higher. It includes signal source, edge blending
processor and the total resolution of the projectors after edge blending.
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If user uses 8x XGA projector with 250 overlapped pixels, the total projector resolution after edge
blending will be 1024*8-250*7=6442 pixels. It means it is enough to use XGA resolution projectors
in this 20m screen case. If user uses FHD or WUXGA high end projectors with watching distance
at 5m, the final video quality will be very similar as XGA projector under 4k signal source at 5m
watching distance.
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We can provide free service to help customers to make project plan, including system
configuration, type of projector, signal source and installation data.
4.2. Determine overlap region size and pixels
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VNS provides an Excel Spread Sheet for user to do edge blending plan.
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Using Excel Spread Sheet calculation, user can determine the overlap region size by different
projector resolution, lumens, image size and number of projectors.
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The most common overlap region is about 20% to 40% based on single projector native resolution.
For 1024*768 projector, the overlap range is 1024*20%-1024*40%=205~409 pixels. GeoBox test
pattern default size is 32x32 pixels. Therefore, the final result will be around 7 grids (224 pixels) to
13 grids (416 pixels) for XGA projector and 12 grids (384 pixels) ~ 24 grids (768 pixels) for 1080p
& WUXGA projectors. If the projector has accurate color and gamma curve, the overlapped pixel
can be lower to 5 grids (160 pixels) in XGA projector. The actual pixel number should be
determined based on the required screen size and the projector model used. Under the same
screen width, if higher image is required, then the overlap region will be also increased.
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User can simulate with different overlap pixels to get reasonable overlap region dimension
between 50cm to 120cm. Reasonable overlap region will be easier for overlap color control.
