Neon Bilboard

[i-d]

Here is a simple copy stamp excersise for a begginer like me,

make an animated neon sign with some interesting effect.

First test is made with trace SOP on image which is going to

be sequence later, hopefully

I made two traces of the image, one for the outline

and another for inside little lamps, which image was shrinked in cops with expand, he,he .

In that shrinked one I put a divide SOP and make it Bricker Polygons with enough

small size to give me a fine quadratic mesh over outline, great thing about it is

that you have offset and angle to play with, instant animation,

but there is a few problems with this simple approach, besides some

bad nesting of points on the trace curve, its not that much controlable,

not in a houdini ways, me think.

I would like to make this a little bit more like an inteligent system,

especially with animated sequence driving it,

I can foresee some problems allready, those P shaped

regions where hands are making another closed shape can make me

a lot of troubles.

so all help is very appreciated.

I will post a hip file as soon as I get it together, its pretty dirty now.

[michael]

cool!

have a look at the resample SOP - it might help control the points coming out of the trace...

looking forward to more...

[i-d]

thanks, I used resample, forgot to mention

but how I make these points to move nicely along the traced curve,

I know there is an expresion somewhere

But lets see if I can upload animation to see

a first, rough effect

NeonFirst.mpg

[rdg]

but how I make these points to move nicely along the traced curve,

speaking of neon signs, those point probably switch on and off instead of moving along a line.

this could be done by grouping every nth point and a sortSOP that shifts the point numbers around.

Your P shaped regions:

Depending on what troubles they cause you can maybe track them down by measuring their area.

Based on this value you can either exclude them or scale them or process them differntely.

Your mention of the divideSOP bricker made try it again as I am still looking for a automated process to pre-hatch arbitrary shapes.

Maybe it is possible to extract lines with a specified normal/direction ...

rdg::crossHatching

Georg

[i-d]

Thanks Georg, you were right on the point

It's true that effect of flowing in neon signs are made

with switching on and of the lamps and I will try your idea

with sort SOP. Did you mean controlling the shading attributes

for switching the lamps off, or something else.

I have allready stamped several shading attributes, dont know

exactly how to switch them of all at once but will try.

Other thing that come to mind is to control size, making them zero to switch off.

As for the measuring area for holes its little to much for me right now but

will shurely try, dont know about moving images, changing shapes rapidly.

Like your hatching test, nice selection of image

I think I'm going to try some test with nurbs, see where's that gonna take me.

[stu]

I've had to do this sort of thing before, and I've always driven the bulb colour by using an animated texture - I copy the bulbs to the appropriate location by modelling an outline of their location, and drive their colour with a point SOP that looks up the animated texture map and applies the colour to the outline that the bulbs are being copied to. This way the animation can be whatever you want it to and you aren't limited by some crazy expression. I'll try to post an example when I get a chance (unless someone beats me to it...I'm looking in your direction, Michael ).

[michael]

it seems of the two of us I'm the only one actaully working today...

[rdg]

dont know about moving images.

The 'problem' of moving images - in my opinion - is that you need to know how your system works.

While I am still not frikkeled enough to visualize the ongoing hatching of a moving character I could imagine how a neon sign reacts.

I'd orientate my self on TFT or something like that.

Where you have a fixed area of items that can be either on or of.

A groupSOP can be used to group the lamps currently inside the shape and therefor on.

Switching multiple shading attributes on/off:

You could have a single on/off attribute and base your shaders on this.

like: if on then color yellow if off then color black.

[i-d]

thanks guys, you're great

stu, thats a nice technique with animated texture for making this even more exciting,

not sure about this case where you could have a fast changing outline,

it would be fantastic if we can combine both.

that sort SOP with shift really saved the day, I was first pluging it

wrong way after the groups, now it works exactly as it should,

right tool for the job.

things are little messy now cause I duplicated spheres with shader attributes

for ON and OFF ones, dont know howto make that switch yet,

but I dont care about that right now, it works, yupii

divide SOP bricker is not the "real" solution, good for most of the

effects, but what if I want lights to originate from center of the

image pulsating outwards, or something else that would look good,

gotta try that next

NeonBC.mpg

[stu]

it seems of the two of us I'm the only one actaully working today...

Yeah, which one of us was still at work at 5:00 this morning?. :sleep1:

As for a fast changing outline, it'll change as fast as your animated texture does. Here's an example:

animated_bulbs.1.hipnc

[michael]

I can't help it if I'm able to get my work done in a reasonable amount of time

[i-d]

Nice and simple Stu, tnx

O.K. now I only need to figure how to group

those spheres according to alpha and another

one is down

[michael]

have a look at the Partition SOP

[i-d]

have a look at the Partition SOP

hmm, Partition SOP that sounds about right, will try

in the mean time I'm facing some other challenges,

making it in 2.5D world, on a curved surface

its just stripe shader animated, copy and all,

no much of SOP magic on this one,

merely little compositing test, las vegas style

SurfaceNeonComp.mpg

this mpeg is skipping some frames a little so the animation

is not as smooth as its from houdini

[i-d]

Here is another little problem that I cannot resolve

I would like my copy/instance tubes to conform to

other surface like on a leaf, see picture,

I know that this flamingo effect can be done in other ways

but I would really like to have it with copy and stamp

I used ray to project them on a leaf and deformig works good,

but how to get that boundary of the leave surface to scale

tubes to fit?

LeafNeon.hipnc

[rdg]

You should try the creepSOP.

If this distorts the geometry - you could try creeping a lattice wich in turn deforms the geometry.

(I am currently compiling an article about creeping lattices.)

Georg

[i-d]

You should try the creepSOP.

If this distorts the geometry - you could try creeping a lattice wich in turn deforms the geometry.

(I am currently compiling an article about creeping lattices.)

thats exactly what I was trying all day, it sounds perfectly logical for this task, but

creep SOP somehow has a mind of its own and lattice is giving me

a division error, even with bound

that article would be fantastic

it seems that I found solution for that back at SESI, its a geometry to grid faces post

http://www.sidefx.com/index.php?option=com...y+center+centre

Edited February 27, 2008 by i-d

[i-d]

here is a little shader test, not very

perfect because there's some issues with above technique

but looks good in motion

I was thinking a lot about procedural glow shader thingy for this effect,

because in mental ray there is a shader that renders a post effect like glow

but in a scene level, so that every glow is visible in reflections or refractions.

It makes quite a difference sometimes

It would be nice to hear some new ideas about this,

I know that it can be done faster and better in post, but..

and when you could control it with copy/stamp like any other

shader, whoouuaa