you can fly!? Learning to use PD Particles for shrubbery in 3D with Blender:
Bridge of Love
by Cristian 'criss' Mihaescu 
visit my website: criss digital art
October 2006
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Hi, my name is Cristian, and I live in Romania, where I compose electronic music. I also have learned to use a few visual tools and 3D graphic programs, including Terragen and Blender. In this tutorial, I'm exploring some ways to use PD Particles to make great foliage, and then I show how I place the pictures of that foliage into a 3D scene of Blender, my favorite 3D program. Blender is free, but also very powerful - a great combination when you can't affod the other, established commercial applications.  PD Particles is not free, but almost, and I like not just the low cost of it - it just is a really cool paint program for starving artists, and seriously also for well established professionals who have spent so much more for other painting tools and are still looking for something to do just that: paint foliage.  I hope that they will take the time to learn about PD Particles. In my opinion, it is a very good tool like you don't see too many others at that price, and it is very focused at the task, so it should be a great companion to whatever tools you use for 2D and 3D. I hope some day there may even be a Mac or Linux version for others to enjoy too (you might want to try it under Wine, or Parallels).
Here's a quick look at the finished image: (click to enlarge)

I will use PD Particles to create a beautiful cartoon sky and add some vegetation in my Blender file.


Like I said, this tutorial will show how I use PD Particles to add vegetation, a painted sky with clouds or other elements inside a Blender scene. 

You can use PD Particles with Blender in a lot of different ways:
  • paint a background image for use as the background of a Blender scene (with clouds, mountains, fog, plants etc). Render your scene in front of that painted image;
  • add plants and foliage to your scene (import them in Blender like "alpha planes" with transparency masks created automatically. Some people call that a billboard polygon. It can be used with fully opaque decals or with an alpha channel for 'holes' or surrounding transparency.
  • add a lot of painted elements and effects and use them with Blender Composite Nodes;
  • create new textures for Blender materials; Even better tools can be found in the 'big brother' of PD Particles, i.e. PD Artist and especially PD Pro, to make animated textures like lava or seamless textures.
  • postwork a finished Blender rendering, by painting vegetation, glow effects, smearing, paper textures etc.
Let's start  by creating the background: blue sky and clouds

Let me say that PD Particles is the best application I have found for painting clouds the way I like them. You can paint hundreds of different cloud types with so many brushes and so much control over the brush settings.

I started with a 2D app called Artweaver, but you can start directly in PD Particles or your other favorite image editor like the GIMP, PS, PSP, etc...  I started with a new 1024x768 document.

I choose two different blue colors and used the gradient tool to obtain a clear sky with a transition of colors that shows a little bit of haze towards the bottom (horizon).

Using the free Dogweaver plugin that sends the image from Artweaver straight to PD Particles,  or by saving to file or the clipboard, I imported the simple sky into PD Particles. The zenith (top) colors were darker blue.

I then liberally paint the clouds using the
Presets -> Oils -> Large cover


Selecting from a Color Well

PD Particles offers a variety of color presets, called color Wells. They are stored in files which end in '.wl'

For my example I used the CloudySky.wl color preset file.


Then, in the 'Brush setting' panel (to the right) I used various opacities with the 'Default' painting mode and a several sizes and opacities with the 'Smear' painting mode.

What I liked is that it all felt so natural when I tried this the first time, it took me very little time to learn and know what I wanted to do.

You can read more about this and other techniques  and learn new methods for painting clouds reading these tutorials:
This time I wanted to obtain only simple white patchy clouds because it will be a cartoon composition. I saved the final image in a png format.



<<< click to enlarge  

My intention was to create a cartoon Blender scene with nature, some hills, a little river, a bridge and some funny characters imported from Poser.

I started modeling the terrain in Blender using the "PET" tool (proportional editing tool), setting the point of view, camera etc.



<<< click to enlarge  










The shader's preview area to the left should now show your painted image as a thumbnail.  If you do a rendering with F12 it should also appear with your painted sky.

Here's another example, using a sky from a photograph, and using the default scene with a cube.

Importing the Background Image into Blender

At this point I wanted to import the background, i.e. the  painted image. Here are the steps to do that in Blender (you can see my setting for the Ambient Occlusion too).  Click the picture to the left to see all steps in a single view.

  1. click the Shade button amongst the 6 panel buttons
  2. select the World (blue mini globe). We're going to define the texture of the world, i.e. what defines the surrounding background
  3. To the right side, in the 'Texture and Input' tab, click 'Add New' to create a new one
  4. click the Texture button. Verify that it shows 'Tex' and change the type to 'Image'. The 'Load Image' option appears - click it, and find the saved picture (jpeg, Png, Tiff... whatever format) which you saved from PD Particles and which contains the Sky with Clouds.
  5. Click the Globe again, and click 'Paper'.  In the 'Map To' tab, Blend and Hori should be enabled.
  6. In the 'Ambient Occ' tab, click Ambient Occlusion to enable it..
Then it's time to do the modeling work in Blender and to import the Poser characters. That is not going to be shown in this tutorial, as we'll focus on the arts where PD Particles is used.
 
Notice that there are a few wide rectangles in the scene on the ground, which appear to be standing on their edges. Those are the planes (billboards rectangles) to be textured with pictures containing foliage with alphas and will be filled with additional PD Particles vegetation. That's really where PD Particles shines!



<<< click to enlarge  



click to enlarge
Painting vegetation

This is truly the strong point of PD Particles. We can paint a lot of different vegetation, save it in an image file with an alpha channel  (png or tga formats are the best IMHO - PD Particles 'likes' Targa and calls it 'Default Targa" but also supports other formats).

Import it in Blender (or other 3D app) like alpha planes or using composite Nodes or Render Layers. I will use the alpha planes but for all who want to use another method, here are some useful links:


I started painting a bush on a black background. To obtain a black background, simply go in the Filter menu -> Color -> Negative command. (if you start from a white background) or right-click on the Erase tool (the big 'X' icon)

I choose one of the huge number of Presets available in PD Particles and in the right panel with the particles properties I adjusted the maximum  number, mass, gravity, velocities, life, splits, size, random factor etc. Customizing all this options you can obtain thousands of different plants from this and other planets.


Then I exported my bush in my default 2D app, Paint Shop Pro 7.

A very good and detailed tutorial to do this is here:
Using PD Particles with Paint Shop Pro

These are my two bushes, captured from Paint Shop Pro. They are ready to be saved in png image file with an alpha channel.
Don't forget to set the black part to be transpared.

Note that you can also create the alpha channel directly from inside PD Particles - two Styles of particles (Line+alpha and Shrinking Line+)  are able to automatically generate a perfect alpha channel along the particle traces. The grass will automatically be opaque and the background be left transparent. You can invert it if necessary.

Color-keying to black in order to determine the transparent parts will work ok as long as no parts in the foliage is black. Since you may likely use the 'Shading' option in PD Particles, it is likely however that the plants growing down will appear black or dark enough for it to be partly transparent. In most cases it would be best to use the styles with alpha-on-the-fly.
Applying the texture onto a plane
  1. right-click the plane to select it (assuming you're in Object mode already. If not, hit 'Tab' first)
  2. click the Shade button and the Material button to add a material, then
  3. click the Texture button, to start defining the textures. Note that in this example we'll define two textures for the material, using the same texture image but into different channels or uses

Click on the space with 'Tex' and the one below to add another texture. Set the Texture Type to Image and Load the image.

Click 'UseAlpha' and 'Clip'. The preview on the left will show the texture against a checkerboard, indicating that it has found and is using transparency masks from the alpha channel.  If you mask appears inverted, click 'NegAlp' as well to use its negative, i.e. invert alpha.

Now we go back to the shader and indicate how both textures will be used. They are of the same picture image file but will be used for color and alpha in one case and for highlights in the other.

Click the shader button next to the texture button (red sphere)

  • Links&Pipeline tab:   Notice the 'ZTransp' option is set (checked).
  • Material tab:             The 'A' value slider is at zero.
  • Shaders tab:             Spec at zero, Hard at zero, TraShad set
  • MapTo tab:              Col (color) and Alpha checked
This sets the main color aspect and uses the transparency mask too. For many this might be enough, if you use just this one and only texture on the shader.

With the second texture, we start very similarly.
The first few tabs show the same values. The last tab, 'Map To', is different: Instead of using color and alpha, we use Nor (normals, i.e. bumpmapping) and Spec (specular).

Note also that the 'Nor' and 'Var' sliders are noth at 1.0

This may add some nice specular highlights as well as bring the foliage out a little bit more into a 3D look, and appear less flat.




click to enlarge

 To summarize this technique:

On the Blender Artists forum you'll find an excellent tutorial written by Gabio about the steps to set an "alpha plane". Here are the main steps:
  • creating a plane and set a material;
  • one or two texture channels using your 32-bit image (with an alpha channel built-in);
  • press the 'UseAlpha' buttons;
  • press 'Col', 'Nor', 'Alpha' and 'Spec' (For MapInput: 'Orco' and 'Flat' are good) - either in a single texture, or over two textures, especially the latter if you actually do have a different greymap picture that should be used for bumpmaps or highlights!
  • set a good value for 'Nor' (bumpmap) and 'Var';
  • set slider: A (alpha) -> 0.000; Ref -> 1; Spec -> 0.000; Hard -> experimental;
  • press 'ZTransp' and 'TraShadow' for real shadows; Transprency shadows will show the shadows cast by the opaque parts of the foliage, otherwise the whole rectangle's shadow will show.
  • Note: press 'TraShadow' (Shaders pannel) for the terrain material too!
Finally, You can see in the final render how the painted bushes, foliage and grass  looks now like real 3D objects, with some bumpmapped depth and casting shadows.

Another interesting idea is the possibility to have a large number of plants (for example a forest), assigning the alpha planes to a mesh with Blender particles. Every particle will have an image with color and an alpha plane.
We have a lot of other possibilities to improve our 3D/2D images using PD Particles. For example we can adjust the colors with the Filter menu to give different tones to various parts of the image, or we can throw a color gradient at it for like effects.  or, we can of course improve the rendered image with a painting postwork.

 

Cristian Mihaescu (aka criss)
visit my art site: criss digital art
October, 2006

  

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