- Hi All,
At IPS 2000, several of us participated in a panel to discuss the need for
planetarium standards. My motivation for organizing this panel was a
frustration over the lack of IPS interest in the obvious need for standards,
and the barring of vendors from IPS committees that would be responsible for
the formation of such standards (is this actually in the by-laws?).
Anyway, Mark Petersen has posted his talk online... I found it to be an
excellent discussion on the topic. Check out:
Mark also started PVCPipeline, a listserv of the Planetarium Vendors
Consortium, an informal group for vendors in the planetarium community to
discuss matters of mutual interest. The listserv has not been very active
yet, but at least a forum exists for such discussions should the desire to
On that forum, I asked SkySkan a few questions regarding their proposed
standards for dome rendering which were unfortunately never addressed. I am
re-phrasing my questions here for general discussion:
1) Why is the "Dome Master" format currently upside down and flipped (as if
one were looking down on the dome from above)? To facilitate easy
previewing, these files should have the theater front or "south" direction
at the bottom of the frame so that unidirectional action appears rightside
up and not reversed (SkySkan's AllSky alignment grid seems to be properly
2) How was the 2,200 x 2,200 pixel number was arrived at for dome masters?
Was this number generated theoretically, or was it based on actual
resolution tests? This gives an effective 3.80 million active pixels on the
dome. Also, what resolution is considered sufficient for full-resolution
AllSky dome masters? We typically use 4000x4000.
3) Does SkyVision use AllSky grids to align their video frames? We are
working on unique grids for aligning video-to-AllSkys that we would submit
for standards acceptance if there was interest in this.
4) It would be useful to have some standard test frames and sequences to
evaluate and benchmark edge-blending, color, resolution, aliasing, etc. We
have some that we use now, but they could probably stand to be refined.
These include concentric color bars, greyscales, rotating cubes, etc. My
idea is that any dome master show created would have these standard test
frames tacked onto the front. Is anyone interested in collaborating on
As most of you know by now, Spitz successfully transferred our Oasis in
Space sky show onto Houston's SkyVision system for Texas2000. We learned a
few things in this process. For instance, the common animation practice of
field rendering (rendering 60 fields per second rather than 30 frames per
second then splitting the frames into fields) is not possible when images
are not directly rendered to the final raster frames. In other words, if
you render orthogonal views onto the sides of a cube, then remap the cube
faces into an equidistant polar format (SkySkan's dome master format) and/or
transform them into your final projector mapped frames, even/odd field
separation is not preserved (i.e. even fields can map to both even and odd
fields on the output frame).
Our ImmersaMax plug-in for 3D Studio Max renders directly to ImmersaVision
format, thereby preserving even/odd fields and allowing us to field render.
We will have to stop this practice if we want our shows to transfer properly
to SkyVision. The alternative is to render at 60 frames per second and
field-split after remapping (thereby requiring twice the number of rendered
pixels, half of which are discarded) which will provide equal quality to
field-rendered material, or render at 30 frames per second and field-split,
which unfortunately provides lesser quality images than we are accustomed
to. Hmmmm... Adhering to standards is not always so easy.
Product Development Manager
U.S. Route #1
Chadds Ford, PA 19317
tel: (610) 459-5200 x27
fax: (610) 459-3830
home email: edlantz@...
*********** Advancing the Science of Awe *************
Just so I don't get into trouble, ImmersaVision and ElectricSky are
trademarks of Spitz, Inc. SkyVision is a trademark of Sky-Skan.
- In response to Ed's letter.
I suggest if at all possible, since this is a "relatively" new field that
standards be set as soon as possible by a joint committee of manufacturers
and users regarding common productions and presentation standards. Mickey