I'm going through some old scenes that I never posted about, trying to finish
them.

For one animated scene, I decided I needed a 'humorous flying police car.'
Here's what I've come up with so far. It's meant to have a dog-like look--maybe
a bulldog!

It's mostly CSG, but the arm struts and what I call the 'mufflers' were made in
sPatch.

By far, the trickiest part of modeling (and the most fun) was making the raised
'outline' around the windshield. (The body and the windshield are just
spheres--but they intersect at an interesting angle.) Modelling that outline by
hand seemed an impossible task, so I came up with an automated technique, a
multi-stage process, which worked out well:

1) as the first step, rendering a hi-rez orthograhic view of the windshield
area, from the top (with NO antialiasing; very important.)

2) In Photoshop, turning that into a high-contrast image, just pure black and
white. (The windshield white, everything else black.)

3) using eval_pigment on the image to find where the 'border' of one color meets
the other--getting just the borderline *positions*. Lots of them!

4) using trace() on the windshield and its surrounding area to place lots of
closely-packed spheres on the borderline-- with the eval_pigment positions used
as the trace shoot_from points (which required some tricky scaling and
translation, by eye--the image_map and the car model don't have a 1:1 size
correlation.)

5) #Writing the union of spheres to a file, so that subsequent renders don't
have to deal with the *slow* eval_pigment/trace routine over and over again
during animation. Then I #included that union back into the scene--which was
MUCH faster to parse.

In actual practice, it was a bit more complicated; but those are the basics.
There are probably other ways of going about this, but I wanted a 'general'
technique (for future use) that I could apply to any finished model.

Originally, I tried just a typical trace() of the car/windshield, making use of
the *differences* in the found normals to place the spheres. That didn't work
well--because those differences are really subtle in places; the windshield
doesn't bulge out that much.

This police car was originally not so detailed, as it makes only a brief
appearance in my scene. But it's a good asset for the future, so I'm looking for
ways to improve it. Suggestions or criticisms welcome.

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Attachments:
Download 'police_car_wip1.jpg' (72 KB)

Preview of image 'police_car_wip1.jpg'

A close-up of the windshield area. (Hmm... it looks like the outline needs even
MORE spheres; or else my technique needs some additional finessing.)

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Attachments:
Download 'windshield_cu.jpg' (127 KB)

Preview of image 'windshield_cu.jpg'

On Sun, 28 Apr 2013 20:20:03 +0200, Kenneth <kdw### [at] gmailcom> wrote:

> A close-up of the windshield area. (Hmm... it looks like the outline  
> needs even
> MORE spheres; or else my technique needs some additional finessing.)

I think it would be smoother with blobs.

I like this, it looks like silicon :)
-- 
-Nekar Xenos-

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"Nekar Xenos" <nek### [at] gmailcom> wrote:

>
> I think it would be smoother with blobs.

Hmm, I didn't think of that. I'll do some experimenting!
>
> I like this, it looks like silicon :)
> --

Thanks. I do wish the arm struts could 'blend into' the body in a smoother way,
though. (Each strut is a bicubic mesh, but the body is just a sphere
primitive.) Or maybe I could re-build the struts AND body in sPatch, so that
they are all one big mesh.

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> A close-up of the windshield area. (Hmm... it looks like the outline needs even
> MORE spheres; or else my technique needs some additional finessing.)
>
How about blobbing those spheres? A sphere_sweep could also be used here.

Both would allow you to use less spheres.

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"Kenneth" <kdw### [at] gmailcom> wrote:
> A close-up of the windshield area. (Hmm... it looks like the outline needs even
> MORE spheres; or else my technique needs some additional finessing.)

How about joining the spheres with cylinders?  (I'd suggest a sphere_sweep,
except that those things are pissing me off again.)

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"Kenneth" <kdw### [at] gmailcom> wrote:
> A close-up of the windshield area. (Hmm... it looks like the outline needs even
> MORE spheres; or else my technique needs some additional finessing.)

Hi Kenneth,

Nice model, I assume the muffler is the bit at the back towards the bottoms, if
not how did you do that shape in CSG?

As several people have already pointed out, I would go for a blob for the window
surround, I tend to always use blobs for this kind of modelling (unless I can
workout a good spline path for a sphere_sweep). If you can workout the spline
(not one of my strong points) then a sphere sweep would be best.

I have been looking through old unfinished scenes as well, mainly ones I gave up
waiting for the renders to complete due to heavy use of isosurfaces but with a
quad core, POV v3.7 and a bit more patience I may get them finished.

Sean

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Alain <kua### [at] videotronca> wrote:

>
> How about blobbing those spheres? A sphere_sweep could also be used here.
> Both would allow you to use less spheres.

Yes, *any* technique to use less spheres (or rather, less scanning/tracing
points in my technique) would be a welcome improvement.

I haven't worked with sphere_sweeps in quite awhile; the artifacts they used to
have (in the v3.6 and 3.61 days) made working with them difficult.  Actually, I
do remember your advice from the past--use *short sections* of sphere_sweeps
(i.e., not too many points) then union those together, which helps eliminate the
artifacts. So I might give that idea a try. It would definitely make a
*smoother* outline than my spheres.

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"s.day" <s.d### [at] uelacuk> wrote:

>
> Nice model, I assume the muffler is the bit at the back towards the bottoms, if
> not how did you do that shape in CSG?

It's another sPatch bicubic mesh. (I wouldn't have any clue how to make that
same shape using CSG!!) I still like using sPatch; it's an *old* app and with a
few quirks; but it has a very simple interface, to build objects point-by-point.
It does only one thing--no bells and whistles--but that's a welcome relief from
the usual (and generally complex) 'application that does everything.'
>
> As several people have already pointed out, I would go for a blob for
> the window
> surround, I tend to always use blobs for this kind of modelling (unless I can
> workout a good spline path for a sphere_sweep). If you can workout the spline
> (not one of my strong points) then a sphere sweep would be best.

I have to admit that working with blobs has never been my strong point; it's
been years since I tried them! But I need to re-educate myself--they seem to be
a really powerful modelling tool. (Especially after seeing Nekar Zeno's
wonderful recent 'melting blob-men' image, of his jazz musicians.)

The spline requirement for the sphere_sweep is indeed a tricky thing to come up
with (re: my particular windshield outline.) What I imagine is that the spline
might not end up exactly following the correct curve. But that's just
theorizing; I should give it a chance, to see what happens.

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On Mon, 29 Apr 2013 08:16:49 +0200, Kenneth <kdw### [at] gmailcom> wrote:

> Alain <kua### [at] videotronca> wrote:
>
>>
>> How about blobbing those spheres? A sphere_sweep could also be used  
>> here.
>> Both would allow you to use less spheres.
>
> Yes, *any* technique to use less spheres (or rather, less  
> scanning/tracing
> points in my technique) would be a welcome improvement.
>
> I haven't worked with sphere_sweeps in quite awhile; the artifacts they  
> used to
> have (in the v3.6 and 3.61 days) made working with them difficult.   
> Actually, I
> do remember your advice from the past--use *short sections* of  
> sphere_sweeps
> (i.e., not too many points) then union those together, which helps  
> eliminate the
> artifacts. So I might give that idea a try. It would definitely make a
> *smoother* outline than my spheres.
>
I guess I've just been lucky with the sphere sweeps. The neon lights in my  
busker scene is all sphere sweeps.


-- 
-Nekar Xenos-

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