I trying to create a fluorescent light for a kitchen scene. the four large cylinders are for checking shadows.

1.) initially i thought to use an environment light on a cylinder. but that takes way too long to render, and i was getting funny shadows. probably because i need to have more facets on the cylinder.

2.) i switched to anything glows, but on the wall, i get a small highlight as if the source were a bulb.

3.) also, fluorescents give off very soft shadows. and when i selected soft shadows with AG, i got no shadows.

4.) next i tried a tube light. again, a single point highlight. (i also tried this with soft shadows, but did not post the image. like the AG, it just turned shadows off.)

5.) when i placed a cylinder over it, the cylinder disrupted the light. the cylinder has a glow color and a transparency value of 100%. also, it was set to not cast shadows.

6.) to test that the ast shadowswas not working with the tube light, i moved the cylinder behind the light. voila! a cast shadow. and yet the properties box has ast shadowsdeselected.

7.) finally i tried a string of bulb lights (40 of them set at 5% brightness).

8.) the cylinder this time does not cast shadows. and the lighting effect looks much more like i desired. i used soft shadows to help blend the light. but there is still too much light on the wall at the end of the room. this would not happen with a real fluorescent, so i still have some problem solving to do.

9.) an enclosure around the lights to try to cut off some of the light hitting the far wall. i tried making two plates for the ends of the light that were about four times the size of the diameter of the tube. i set them to not be visible but to cast shadows. i placed them at the ends of the cylinder, but they did not seem to block the light from the bulbs.

these are the things that i have tried so far. if anyone has any suggestions, i would be greatly appreciative. i would like to stay away from environment lights if possible since my computer is super slow and i don have the patience to wait a half hour for a 320x240 test render.

thanks for your help.

-scott

Hi Scott, For the highlight that appears on te wall, my advice would be to simply edit its shader and put 0 in the highlight field . Simple, but effective ;) For the light, if you use a row of 5-6 bulbs with soft shadows, you should get something that looks good and renders quickly ... if you have enough RAM for the soft shadows . I hope it helps, litst

hi litst,

thanks for the advice. i actually want to maintain a highlight on the wall and other surfaces. i want the highlight to be the same shape as the light source (as it would be in real life).

since you've done quite a bit of playing with environment lights, do you have any input as to why my first image had such a strange shadow. as i said before, i'm not gonna use EL for this image, but i'm interested in knowing more about it since i hope to one day get a better computer.

thanks again for your input.

-scott

Actually, i think there are two reasons why your first image doesn't look good . I'll try to explain you what Environment Lightning does when you add it to an object . Basically, it adds some Anything Glows lights in the scene, on the facets (triangle) of your object . Just open your sequencer tray and expand the EL group attached to your object and you'll see what i mean . The place of these new lights depend on the facets, like i said, so if there is a concentration of facets in a area of your object, the AG lights will concentrate in the same area . And of course, the emitted light will not be regular . See the settings i've used for my neon tube : it's just a simple cylinder, but it has a lot of facets disposed regularly . The second reason is basic : don't make your cylinder cast shadows . So edit its properties to disable the 'cast shadows' option, and it should be better . And you know, you can use EL even with a slow computer, with some tricks . The image you see has rendered in 23 seconds on my AMD 1400, and the scene has 333 lights ! I've already explained those stuff in some previous posts, anyway i'm sending you my render settings : you'll get the fastest render with this :) . But don't forget to put the 'sampling' options off when you render your final image ! Hope this helps :) litst

For the row of 40 lights, you should set the falloff to be 100% and change the falloff distance to be appropriate for your scene. I've had very good success with that. -Kix

hello litst, kix, and anyone else who's interested...

i played a bit with the settings you gave, litst. seems your machine is about 3 times faster than mine. sigh.

anyway, the shadows still band a bit. i suppose adding more segments and facets will solve this problem, but that will also slow down rendering.

the final image will have a lot of transparency and reflection, so i'm probably going to go with bulbs.

i tried a row of 7 bulbs, but the highlight begin to separate. back to the string of 40 and kix's idea of turning the fall off to 100. this did a decent job of reducing the light cast on the far wall.

i think i'm going to experiment more in that direction.

thanks out to both of you for giving me input on this.

-scott

You're welcome :) For the lines that appear with EL, don't worry too much about them . When your scene will be textured, they will not be as noticable as on a very clean surface (see the pic) . Also, if you want the light to go through tranparency, don't use soft shadows of your bulbs !

yeah, i already knew about the limitations of shadow-mapped soft shadows. fortunately, i won't need to focus on the shadows that my transparent objects are casting. also, for the final image, i'm planning on rendering in several passes. i'm thinking about rendering one pass of the fluoresecent with raytraced shadows, another with soft and tweaking as needed in photoshop. we'll see. -scott

Can this be done in RD5? I apologize in advance for asking.

Don't apologize, Duane, the forum is here for asking questions :) Anything Glows that is used for Environment Lightning does not exist for RDS, only Carrara (and version 2.5 is part of Carrara Studio) . There are soft shadows in RDS, so you can definitely use them with a row of bulb lights to simulate a neon . Plus, in RDS the soft shadows can go through transparency :) litst