Starfield Animation question



  • I have an HDRI spherical environment map. This one happens to be a deep space map. Here's what I would LIKE to do and I need some advice on how I might be able to make it work. I want to animate the starfield so that it looks like you're on a spaceship and the stars outside are flying by the window. The simplest method of how I might make this work is to apply the map to an environment sphere using Snarly's EZ Dome. And Animating the sphere to simply rotate. I'm not talking about traveling at warp, light or hyperdrive. I just want the stars to travel past the window like trees do if you're driving down a highway. Any advice from the animators out there?



  • The reason I like this method is not only because it's simple, but if it works you could also apply it to a sky map and have clouds slowly drifting past a window.



  • If you don't travel with warp speed you need to move the stars really slowly. Really slowly. Like, no visible movement in the first couple of decades.

    Rotating the sphere will look strange, I guess it would be better to move the ship and the camera. Even better would probably the Image mapped on a cylinder and moving the cylinder.



  • @bantha said in Starfield Animation question:

    If you don't travel with warp speed you need to move the stars really slowly. Really slowly. Like, no visible movement in the first couple of decades.

    Rotating the sphere will look strange, I guess it would be better to move the ship and the camera. Even better would probably the Image mapped on a cylinder and moving the cylinder.

    I'm not particularly interested in how it looks as long as it works. And we're talking about being on the inside looking out. Think more like a space station. The station would spin to create artificial gravity so I'm thinking something that looks like this:



  • @eclark1849 you are definitely on the right track.


    This starfield is magnitude 4 and brighter on an environment sphere slaved, with the sun sphere, to an orbiting infinite light (unnecessary for your purposes) doing a 360 degree orbit, while the dolly camera follows the direction of the sun during it's daylight hours then pans around to meet the sunrise position at the end. All of the rest of the scene (beach, water, sky and cloud environment spheres) has been hidden.



  • @eclark1849 the camera focal length in that animation is 12.5mm, i.e. rather wide angle, so picking something longer, like 50mm or 100mm will cut down and space out the number of stars you see in the field of view, appearing more like your own video.


  • Poser Ambassadors

    @eclark1849 said in Starfield Animation question:

    Animating the sphere to simply rotate.

    If you want the appearance that the ship (and the observer) is rotating, then this.

    I'm not talking about traveling at warp, light or hyperdrive.

    Traveling in a straight line and not rotating? If not warp speed, then the stars would not visibly move for centuries. You must be talking about warp speed (faster than light).

    I just want the stars to travel past the window like trees do if you're driving down a highway.

    So warp speed.

    Please clarify. Rotating like you're on a space station NOT MOVING, or traveling through space at super-light velocity.



  • @bagginsbill I did clarify that I was talking about rotating like on a space station. Honestly, I'm not even sure I buy the warp speed faster than light movement starfield representation. The closest star to Earth aside from our sun is Alpha Centauri which is 4 light years away which means that traveling AT light speed it would take us 4 YEARS to get there. SO even if you say we travel at 4TIMES the speed of light it would still take at least a year to get there. That star is not going to be whizzing past any viewports anytime soon.



  • @eclark1849 back to the stars flying by the window, The environment map I'm using was actually generated from a data set which included the directions, distances and apparent colours of the visible stars. The distributor had set up a LightWave scene and exported an obj file which defined each star as a point in space! Most unfortunately, Poser can't deal with (well, it can import them, but it has no mechanism to display in preview or render) points, so I had to resort to taking on a one month free trial of LightWave, just so that I could render that data set to an environment map.

    If Poser did support Wavefront OBJ points, then you could fly through the stars within your scene!


  • Poser Ambassadors

    OK so rotating the sphere is a perfect solution. There are only two things to consider.

    What speed? What orientation?

    Speed: I'm sure you don't want the math. Proposals are typically involving less than the full force of earth gravity and various sizes of wheel. I'll just give data for a wheel with a 250 foot diameter.

    angular speed = 9.0 degrees/sec, rotation time = 40.0 sec, acceleration = 0.10 g
    angular speed = 12.0 degrees/sec, rotation time = 30.0 sec, acceleration = 0.17 g
    angular speed = 15.0 degrees/sec, rotation time = 24.0 sec, acceleration = 0.27 g
    angular speed = 18.0 degrees/sec, rotation time = 20.0 sec, acceleration = 0.39 g
    angular speed = 21.0 degrees/sec, rotation time = 17.1 sec, acceleration = 0.52 g
    angular speed = 24.0 degrees/sec, rotation time = 15.0 sec, acceleration = 0.69 g
    angular speed = 27.0 degrees/sec, rotation time = 13.3 sec, acceleration = 0.87 g
    angular speed = 30.0 degrees/sec, rotation time = 12.0 sec, acceleration = 1.07 g
    angular speed = 33.0 degrees/sec, rotation time = 10.9 sec, acceleration = 1.30 g
    angular speed = 36.0 degrees/sec, rotation time = 10.0 sec, acceleration = 1.54 g

    You can pick your target acceleration (g) from the above. I suggest 18 degrees/sec (three revolutions per minute). So if you're animating a scene for 10 seconds, rotate the sphere 180 degrees from start to finish. This simulates .39 g - a comfortable and safe force for living in space.

    As for the orientation: Assuming the typical poser camera looking along the Z axis towards your wall with the port/window, this would be the axis you want to rotate on - Z.


  • Poser Ambassadors

    For a bigger wheel in space (say, 356 feet diameter, which is how long the ISS is at the moment)

    angular speed = 9.0 degrees/sec, rotation time = 40.0 sec, acceleration = 0.14 g
    angular speed = 12.0 degrees/sec, rotation time = 30.0 sec, acceleration = 0.24 g
    angular speed = 15.0 degrees/sec, rotation time = 24.0 sec, acceleration = 0.38 g
    angular speed = 18.0 degrees/sec, rotation time = 20.0 sec, acceleration = 0.55 g
    angular speed = 21.0 degrees/sec, rotation time = 17.1 sec, acceleration = 0.75 g
    angular speed = 24.0 degrees/sec, rotation time = 15.0 sec, acceleration = 0.98 g
    angular speed = 27.0 degrees/sec, rotation time = 13.3 sec, acceleration = 1.24 g
    angular speed = 30.0 degrees/sec, rotation time = 12.0 sec, acceleration = 1.52 g
    angular speed = 33.0 degrees/sec, rotation time = 10.9 sec, acceleration = 1.85 g
    angular speed = 36.0 degrees/sec, rotation time = 10.0 sec, acceleration = 2.20 g

    For this size wheel, 15 degrees/sec (.38g) is better but even the previous 18 is believable (.55g).