Local TutorialMatching Lightwave classic and advanced camera (single point polys)

mcooney

I use lightwave, and always loved making my space scenes with the single point polygons. When LW9 came out, great new features, one in paticular, the advanced camera with realistic barrel distortion, but the usual way of rendering stars would dissapear if i used the advanced camera.

I could render the stars seperately with classic camera, but if i tried compositing with a spherical projected advanced camera render, the barrel distorted advanced and the pincushionyness of classic meant the perspective would never match up.

After many trials and errors and thinking about how one could get matching diagonal FOV's when it normaly couldnt, i found out a way to get classic camera to match advanced camera perfectly, barrel distortion and all.

Here's how i did it. I first set up to render with the advanced camera, ray direction set to field of view. Carefully setting and remembering my desired horizontal FoV. Say for now i set it for 70 degrees. also setting up my frame aspect ratio. 1.77 or HD.

For a starfield pass with classic camera, I type in 70 degrees for field of view, where it says "FOV" it will list 70 degrees by 43 degrees.

Now i take the vertical FOV, go to horizontal FOV select, i type 43, and press asterisk, to MULTIPLY 43 degrees by the frame aspect ratio, or 1.77 . It would get a new width of 76.11 degrees. Render this seperately for backgrould stars only.

Now i need this to warp back onto advanced camera perspective. To do this, you can take a single self luminus polygon, place it right next to the camera. Load the image sequence of the stars, and select front project for a texture on the polygon. In camera, select advanced camera spherical projection again, putting back the original FOV of 70 degrees. Render a new sequence.


This process does blur the image somewhat so for the stars, i'd do a 150% normal resolution, but hey, it's just points. The new warped image sequence could be now set as a background sequence for compositing.

DAve

Sounds interesting, but I'm somewhat lost.

Any chance you could post some images of what you are describing?

DAve

mcooney

I have had some internet problems, but am putting some attached images that illustrate what i did.

The first pic BA-PLATE is a foreground object with the same 70 degree field of view i used in my text post. In enviroment panel, under plugin textured enviroment, i put in a spherical map of a registration grid i made just to illustrate the perspective lines. Ba-plate is rendered with advanced camera, horizontal FoV set to spherical 70 degrees. A single point polygon starfield is in the scene, but of course is not visible.

Second picture BA-STARS-CLAS, the foreground object is made invisible or can be deleted. Camera set for classic camera, and for this case, i doubled the resolution. The starfield's size and brightness are already exagerated here for illustrative purposes. I took displayed vertical Fov, 43 degrees. multiplied by 1.778 equals 76.46 degrees which becomes the classic camera horizontal FoV.

For third pic, BA-STARS-WARPED, cleared scene, had problems with polygon, so i went with textured enviroment plugin, for front projection purpuses set the the scale in the menu small, way small, 0.001mm, for the texture, select, ba-stars-class. For this to work, you got to set classic camera proper size before opening advanced camera, so i set it again to 76.46 degrees horzontal, opened the advanced camera, but set it to the original 70 degrees, dont ask me to explain, i dont know exactly how but it works.

Forth picture, BA-STARS-COMPED. Reloading original scene or loading the original foreground minus starfield, with alpha channel, and load the image of ba-stars-warped. In compositing window, ba-stars-warped placed in background images. For this pic, i just rerendered the plate, removing the registration grid from the bakground.

al3d

you know there are way better ways of doing this with either star pro or hyperstar right?...and with even better results!...

IRML

you lost me a bit reading all that, but I see the point about not being able to render single point polys with the advanced camera and wanting to try and work around it, I used to do all my starfields with single point poly domes before v9, but now I'd rather just find a new and better way of doing the stars than go to all the trouble of making things match

this could come in handy for other things though

btw if you turn off AA it shouldn't blur the image, and it'll render it out quicker, just put the 2 together and do some motion blur in post

DAve

Thanks for the images mcooney.

Another alternative I seem to recall I have used in the past is to replace the single point starts with hypervoxels.

DAve

Edit: I'm still a noob at rendering so my scenes/lighting is so unoptimised it does not make much difference to my rendering times - no doubt when I improve in this area I may want a quicker solution

mattc

Needless to say, that NT will address 1 and 2pt polygon rendering in future updated of 9.x

M

Mr. Wilde

al3d wrote: »

you know there are way better ways of doing this with either star pro or hyperstar right?...and with even better results!...

That's right, but all those cost extra money. And it's bad in general to lose a feature you got used to.

mcooney

One of the reasons i tried this is i'm kinda poor and i even if i wasn't, i generaly prefer to solve a problem with something straight out of the box before resorting to purchasing a plugin.

I did find a free demo to something called StarPro, just from the demo, this was created before LW9's new cameras, and my test pictures really were messed up if i tried using advanced camera. Haven't tried the Starfield plugin, but trom the website, it looked like it's designed only for a classic pinhole camera type setup.

PS there is some photoship or paint shop pro methods of just rendering a regular scene and adding the barrel distortion in post, but it tends to cause peeling of the image around corners and the center bulges and gets blurry, so you'd have to spend extra rendering time for an image that's gonna get cropped and reduced in size.

When i warp the image of the single point polygons, i do use a higher resolution, but only for that layer, and i don't have to crop or oversize res my foreground.