#PropBlur-LW
17 messages in this thread
Folks:
Does anyone out there have the correct motion blur and rotation settings for
realistic aircraft prop motion in LightWave. Like the example shown in the
short LightWave 3.5 demo tape.
I can't seem to stumble on the right settings. Doh!
Thanks,
Trent/ReAnimators
Trent I dont know what the RPMs are for a airplanes prop but the 50% default
setting seems to give you the most realistic level of blur. The RPMs are
probibly above 2800RPM so divide by 60 is 46.666 per second, divided by 30 is a
bout 1.5 revs per frame. I guess….
Brad Hayes
Hayes Visual Communication
My Cessna 172 runs with max. 2800 RPM (red line). Normal cruise setting is
between 2350 and 2500 RPM. Mybe this helps.
Regards
***Volker Lauke***
via AutoPilot 1.80
Volker:
Thanks I took ground school 14 years ago, I never did get in the air
though… I'm amazed I was that close.
Brad Hayes
Hayes Visual Communication
Thanks Brad, I'll give it a try!
Trent/ReAnimators
Actually, realistic RPM for non-jet (i.e. piston powered) props is in the
2100-2500 rpm depending on whether you are in cruise, climb or decent mode.
Most normally aspirated and fuel injected AC engines are close to an over-speed
condition at 2800. It is also somewhat dependant on the prop and whether it is
fixed pitch, climb or cruise optimised or variable pitch (aka constant speed)
prop.
If you want realistic speeds for different flight conditions, the following are
good for most general aviation prop planes:
Climb-out 2700; Cruise (economy) 65% power: 2100; Cruise (pushing it) 75% power
(which is about all you can get at altitude) 2400; Cruise climb (gradual ascent
that is a compomise between rapid altitude gain and cross-country travel) 2500;
Cruise decent 1700; approach to landing (on final, essentially with the power
nearly off, and gliding in) 1100.
Now, for the lightwave part: 2400 is bad because it is evenly divisible by 30
and 60. In order to not get an "interference pattern" or an apparent no motion
condition with interlace, I would use 2350 or 2300 or 2450. Then try a run with
field rendering without motion blur. Then up the motion blur percentage until
it looked satisfactory. It could also be faked with a highly transparent disk,
two slightly less transparent blade shadows (solid, like maybe an elliptical
cylinder with its axis along the line of the prop blade) with high edge
transparency that vibrates back and forth quickly in a very short arc (like
maybe +/- 5 deg) and the transparency quickly alternating between say, 100 and
93%, but not at a rate evenly divisible by the vibration rate.
Unless absolute mechnical accuracy is demanded, it seems one should rather
think in terms of the animation realities involved. No matter what rate you
spin it you'll only see at most 60 discreet positions per second. With a 2
blade prop this is the same as 30 unique positions of the blades due to the
symmetry of the blade. So something even as low as .9-1.1 RPM with field
rendering and motion blur might do.
wmc – via Autopilot!
Wayne:
I was only guessing of the top of my head. But since you went to the trouble
to list it so concisly, maybe you should think about an artical for LWPRO.
sounds like the ground work is pretty much layed… 8)
Brad Hayes
Hayes Visual Communication
PMFJI,
but I just wanted to second Brad's suggestion that you write an article for
LWPRO on the finer points of motion blur and blade rotation. I think you
offered some good food for thought on real vs. perceived speed, and adjusting
the rotation to avoid syncing with video frame rates. Perhaps you could do
Waring Blender speeds next: Blend, Chop, Mix, Puree… 😉
Sean Hannon
Ad Rats – Stamford, CT
Maybe I should get out and fly a little more. Maybe go to an Airshow and get
stats for all the old Warbirds – THEN write an article and write-off the
airshow trip :^}
Actually, I was going to play with the problem a little when I get a chance.
It is an interesting problem when you throw in the interlace consideration.
wmc – via Autopilot!
>>Actually, I was going to play with the problem a little when I get a
chance.<<
FYI, I wanted to implement the blur effects in an animation I've been playing
with after watching "The Right Stuff" recently. I have an excellent B29
Stratofortress I DL'd from Media Zone, and am working on building a Bell X-1.
I'd like to show the plane airborne, then dropping the X-1, and it blasting
off. Should be a good way to enact the blur effects for the B-29's props, as
well as a good test for rocket-style exhaust effects from the X-1. Now I just
wish I'd gotten around to getting the Pyromania CD…
Cheers!
Trent/ReAnimators
Thanks for the info, Wayne! As my original message stated, I'm looking to
re-create the blur on the LW 3.5 demo tape. I'll give those settings a try.
Trent/ReAnimators
Trent,
I don't think I've seen that demo tape.
Let me know where you end up with the settings. I miay have some time to play
with it next wee. If I come up with anything that looks like it will help I'll
send 'em along.
wmc – via Autopilot!
>>I don't think I've seen that demo tape.<<
It was the very short one that came out with 3.5. Had a sequence showing the
phonebook commuter plane object with blurred props. The video began with a
short emmy animation and a v/o of the emmy presentation.
Trent/ReAnimators
All I got with 3.5 was a white envelope, some disks and manual pages that
didn't seem to fit in the existing LW sections of the book – unless you are
talking the stand-alone which I don't have.
wmc – via Autopilot!
If memory serves, the tape came separately, but before stand-alone. In any
case, it wasn't much, except for the prop thing…
Trent/ReAnimators
Try using about 19200 revs for about 240 frames.
Steve Cole
Thanks Steve, I'll give it a whirl. (so to speak)
Trent/ReAnimators