Reuben Pearse wrote:
> Thanks for trying your macro.

No problem.

> I will find the POV code I used for the colouring picture and perhaps 
> you could try your macro with this instead (it seems that mesh2 files 
> created from DXF files via PoseRay work best with the PovEdge macro).

Sure, if you find it, I'll try it again.

The attached image shows the result of an edge-finding function I just 
slapped together. To make it work, I first rendered the helicopter with 
three (R,G,B, X,Y,Z) slope pigments. The image was subtracted from a 
blurred, averaged version of itself to find the edges. There are still a 
lot of details missing. If there were spaces between the bricks, or if 
the bricks were beveled, it might look better. As it is, it's not very 
useful for a coloring page :(

Sam

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Attachments:
Download 'postedges5_03.png' (147 KB)

Preview of image 'postedges5_03.png'

stbenge wrote:
> Reuben Pearse wrote:
>> Thanks for trying your macro.
> 
> No problem.
> 
>> I will find the POV code I used for the colouring picture and perhaps 
>> you could try your macro with this instead (it seems that mesh2 files 
>> created from DXF files via PoseRay work best with the PovEdge macro).
> 
> Sure, if you find it, I'll try it again.
> 
> The attached image shows the result of an edge-finding function I just 
> slapped together. To make it work, I first rendered the helicopter with 
> three (R,G,B, X,Y,Z) slope pigments. The image was subtracted from a 
> blurred, averaged version of itself to find the edges. There are still a 
> lot of details missing. If there were spaces between the bricks, or if 
> the bricks were beveled, it might look better. As it is, it's not very 
> useful for a coloring page :(
> 
> Sam
> 
> ------------------------------------------------------------------------
> 
That looks great! Your macro seems to do a better job on certain parts 
of the image such as:
1) The line at the top of the propeller blade
2) The inside of the propeller blade
3) The handle on the door

..but I'm guessing that this may be do with the angle at which the 
camera is viewing the object?

I've now uploaded the POV source files that I used to create the 
helicopter colouring page. See link below:
http://www.pearse.co.uk/lego/colouring/helicopter

I think for certain types of shape, your macro may render a better 
result. I created a colouring page of a Star Wars Battle Droid using the 
  same technique, but the PovEdge macro picked up to many edges on the 
battle droids head. This can be seen on the following link:

http://www.pearse.co.uk/lego/battle_droid.html

If I upload the source of the battle droid image would you mind trying 
your technique with that model?

Reuben

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Reuben Pearse wrote:
> stbenge wrote:
>> The attached image shows the result of an edge-finding function I just 
>> slapped together.
>>
> That looks great! Your macro seems to do a better job on certain parts 
> of the image such as:
> 1) The line at the top of the propeller blade
> 2) The inside of the propeller blade
> 3) The handle on the door
> 
> ..but I'm guessing that this may be do with the angle at which the 
> camera is viewing the object?

Well, because it's a post-processing effect, anywhere there's a sharp 
difference between one color and another is where the method will place 
a line. It's a completely visual process and does not care whether an 
object is a mesh or not, so you don't gain access to any special mesh 
information.

> I've now uploaded the POV source files that I used to create the 
> helicopter colouring page. See link below:
> http://www.pearse.co.uk/lego/colouring/helicopter

OK, I'll give it a try. I'll also try the original .obj file as well, 
since I woke up with an idea in mind. How are you at manipulating 
meshes? Can you, say, take a mesh, select polygons, and then apply 
different colors to them? I ask because blocks can be colored randomly 
to create the necessary color difference for my method to work. The 
lines between bricks should then become visible. I'll give it a go later 
on and post something if I make any headway.

Also, last night I came up with a one-step process using MegaPOV which 
renders pretty quickly, all things considered. I'm using the LGEO Lego 
parts library to test with (slower than a mesh), and those blocks are 
beveled. But if my coloring technique for meshes works out, there won't 
be any need to use LGEO. Getting away with only a single render pass 
using MegaPOV would lighten the overall process.

> I think for certain types of shape, your macro may render a better 
> result. I created a colouring page of a Star Wars Battle Droid using the 
>  same technique, but the PovEdge macro picked up to many edges on the 
> battle droids head. This can be seen on the following link:
> 
> http://www.pearse.co.uk/lego/battle_droid.html

Ah yes, the outside edges of some rounded surfaces are hardly visible, 
and some convex edges are much too apparent.

> If I upload the source of the battle droid image would you mind trying 
> your technique with that model?

Sure, but it might be better to have an .obj mesh, depending on what 
kind of progress I make today.

Hopefully in the end you'll find a process that works for you! Maybe 
some other people around here will chime in with some ideas :)

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stbenge wrote:
> Also, last night I came up with a one-step process using MegaPOV which 
> renders pretty quickly, all things considered. I'm using the LGEO Lego 
> parts library to test with (slower than a mesh), and those blocks are 
> beveled. But if my coloring technique for meshes works out, there won't 
> be any need to use LGEO. Getting away with only a single render pass 
> using MegaPOV would lighten the overall process.

Attached is an image showing my progress so far. I randomly changed some 
brick colors to highlight the spaces between bricks. It was rendered in 
MegaPOV in a single pass and took 5 minutes, 41 seconds to render with 
one core. You can see how the pegs break up here and there. Some of the 
lines also seem to extend over others in funny places. It seems that 
there's always a trade-off when finding edges. The missing line on the 
propeller was my fault; I forgot to change the brick color there. The 
missing lines under the front of the cab were caused by a lack of 
definition in that area.

I'll post an image to help explain how I needed to color the bricks 
differently.

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Attachments:
Download 'edgefinder5_41.png' (34 KB)

Preview of image 'edgefinder5_41.png'

stbenge wrote:
> I'll post an image to help explain how I needed to color the bricks 
> differently.

And here's what the function uses for input. Anywhere two bricks of the 
same color meet, I had to change the color of one. I didn't change the 
entire brick color, since it wasn't needed.

Maybe if you use this method, you could make an extra model in which 
bricks of the same color never touch each other? Or is there an option 
somewhere which would let you add spaces between bricks? That might be 
better, since it's kind of a pain to change brick colors by selecting 
polygons and then having to export the mesh again, thus contending with 
improper normals being generated. But even just assigning bricks 
different colors in the Lego program you use would be better than 
selecting polygons and changing colors.

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Attachments:
Download 'edgefindercolors.jpg' (37 KB)

Preview of image 'edgefindercolors.jpg'

stbenge wrote:
> Attached is an image showing my progress so far.

Oops, I left a bunch of stuff out of that one. Here's another version 
that shows more of the edges. I changed the camera position slightly and 
the light_source, and now the pegs looks even taller than they did. this 
method is very touchy. It might as well be a MEGA Bloks model. Heck, if 
it were any worse, it would start to resemble something you would make 
with American Bricks.

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Attachments:
Download 'edgefinder8_10.png' (36 KB)

Preview of image 'edgefinder8_10.png'

Hello,

I have not been very active recently, but I'm happy to see that PovEdge 
is used ! And happy too that other people are developping alternative 
techniques (go on Sam :-) !)

Transparent objects should be ok with PovEdge : just give a fully 
transparent texture to the windshield (like rgbt 1), and you should be 
able to see the edges of the objects behind it (I have done that many 
times for the windshield and windows of cars).

For the problem with the droid head (some message further in the 
thread), did you try reducing the threshold for the crease edges 
(parameter EdThresh) ? Btw on your picture, the silhouette edges seems 
that have a color lighter than black, is this on purpose ?


Thibaut





> Hello everyone!
> 
> I've created another Lego colouring page based on the Police Helicopter 
> set 645.
> 
> This image was created using a combination of MLCAD, LdrDat2Dxf (by Rolf 
> Redford), PoseRay, POV-Ray 3.6 and the PovEdge macro (by Thibaut 
> Jonckheere).
> 
> I created the black and white image by setting all the objects to white, 
> and then used the "outdoor radiosity" option from PoseRay. I had to add 
> a couple of extra light sources to saturate the image with light. I had 
> some problems trying to maintain the transparency of the windscreen, but 
> happy with it for now (I'm not sure how the PovEdge macro copes with 
> transparent objects - perhaps I need to do some more experiments).
> 
> Does anyone have any other tricks for creating these kind of images 
> (i.e. rendering shape outlines of 3d objects)?
> 
> You can download printable PDF's and other 3D model formats, including 
> POV-Ray scene files at the following links.
> 
> http://www.pearse.co.uk/lego/colouring/helicopter/
> http://www.pearse.co.uk/lego/models/helicopter/
> 
> Bye for now
> 
> Reuben
> reu### [at] pearsecouk
> 
> 
> 
> ------------------------------------------------------------------------
>

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PS : to reduce aliasing (visible on some parts of your helicopter), one 
simple effective technique (in addition to parameters like +a0.0 +am2 
+r3 ...) is to render the picture on a larger size, and then rescale 
with some image manipulation tool. Usually, render time is not a problem 
with this kind of picture, so it is possible to render very large images.


Thibaut



> 
> Hello,
> 
> I have not been very active recently, but I'm happy to see that PovEdge 
> is used ! And happy too that other people are developping alternative 
> techniques (go on Sam :-) !)
> 
> Transparent objects should be ok with PovEdge : just give a fully 
> transparent texture to the windshield (like rgbt 1), and you should be 
> able to see the edges of the objects behind it (I have done that many 
> times for the windshield and windows of cars).
> 
> For the problem with the droid head (some message further in the 
> thread), did you try reducing the threshold for the crease edges 
> (parameter EdThresh) ? Btw on your picture, the silhouette edges seems 
> that have a color lighter than black, is this on purpose ?
> 
> 
> Thibaut
> 
> 
> 
> 

>> Hello everyone!
>>
>> I've created another Lego colouring page based on the Police 
>> Helicopter set 645.
>>
>> This image was created using a combination of MLCAD, LdrDat2Dxf (by 
>> Rolf Redford), PoseRay, POV-Ray 3.6 and the PovEdge macro (by Thibaut 
>> Jonckheere).
>>
>> I created the black and white image by setting all the objects to 
>> white, and then used the "outdoor radiosity" option from PoseRay. I 
>> had to add a couple of extra light sources to saturate the image with 
>> light. I had some problems trying to maintain the transparency of the 
>> windscreen, but happy with it for now (I'm not sure how the PovEdge 
>> macro copes with transparent objects - perhaps I need to do some more 
>> experiments).
>>
>> Does anyone have any other tricks for creating these kind of images 
>> (i.e. rendering shape outlines of 3d objects)?
>>
>> You can download printable PDF's and other 3D model formats, including 
>> POV-Ray scene files at the following links.
>>
>> http://www.pearse.co.uk/lego/colouring/helicopter/
>> http://www.pearse.co.uk/lego/models/helicopter/
>>
>> Bye for now
>>
>> Reuben
>> reu### [at] pearsecouk
>>
>>
>>
>> ------------------------------------------------------------------------
>>

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And yet another version with the light's position changed slightly. I 
think I'll quit for now. It's been fun :) I dropped the MegaPOV file for 
finding edges over at p.t.scene-files in case you're interested:
http://news.povray.org/povray.text.scene-files/thread/%3C4c1beb00%40news.povray.org%3E/

I'm not sure it will work for your purposes, since there are still many 
errors present. If I could discover a way to keep the lines from 
drifting in weird ways, it could be more useful. There is still one more 
idea I have left to try, but it's a long shot.

I took a gander at your helicopter-colouring files, and I'm not sure I 
can make that method work with mine. Also, I got my edge pattern to work 
with an obj file of the helicopter, but really ugly effects crop up.

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Attachments:
Download 'edgefinder8_01.png' (36 KB)

Preview of image 'edgefinder8_01.png'

Thibaut Jonckheere wrote:
> 
> Hello,
> 
> I have not been very active recently, but I'm happy to see that PovEdge 
> is used ! And happy too that other people are developping alternative 
> techniques (go on Sam :-) !)
> 

Hi Thibaut,

It's great to see you posting again. Thanks for contributing to the 
discussion.

I've enjoyed using your PovEdge macros, but there are probably lots of 
options and settings that I haven't explored or understood :-)

Would it be possible to amend the macro so that it somehow visually 
labelled each edge that was drawn with a number? You could then 
optionally instruct the macro not to draw certain edges by passing it a 
list of edges numbers. As well as giving greater control over the 
render, it could also provide a way of creating "dot to dot" type 
colouring pictures (see example links below).

http://www.lego.com/ToyStory/en-us/Downloads/Dot-to-Dot.aspx

Let me know your thoughts on this.

Reuben
reu### [at] pearsecouk

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