Creating a Tree with the Particle System

Posted by admin on January 27, 2008

There are several vegetation systems in 3d faculty. One is modeled Mesh
system (being a headache for the scene for its complexity and also time
consuming business). Another is just mapping of photograph-done pictures of tree
onto plane billboard. However, I am now presenting a system which is something
in-between of the above-mentioned two systems in 3DSMAX. It is a tutorial for
advance level. So I will not show the screenshot with every step/paragraph.

TRUNK-BRANCHES

Note: You may have your own pre-made trunk-branches and you can use that
ignoring this section. I will just describe to make a very simple trunk
and very few simple branches.

1) Create a Cylinder in the middle of the scene. Height or Radius
are as of your choice, but should be reasonable. You may like to lower
the Sides value to 10 or so. This cylinder is our base-trunk. It will
then produce some branches (in this tutorial very few branches will be
added).

2) Add “Taper” modifier onto the cylinder. Adjust the Taper Amount
to a negative value.

3) Then, add “Bend” modifier. Give a little Bend Angle. Your
Cylinder should be similar as the picture below.

the Cylinder after applying Taper and Bend modifier

4) Convert the Cylinder into an “Editable Poly”. In Vertex
sub-object mode, move the 3rd , 4th and 5th rows of vertices near
each other. Don’t worry about the precision. You may have your own
vertex refining technique.

moving the vertices

5) Then in Polygon sub-object mode, select a polygon.

selected vertex

6) In the Command Panel of the Modify Tab scroll down to the Edit
Polygons roll-out. Click “Hinge from Edge” button.

7) In the viewport, drag from the upper edge of the selected polygon
to the down to tell the software from which Edge (here the Upper Edge)
this polygon will be hinged. Your Cylinder should be something like the
picture below.

Polygon after hinged from edge

Now, extrude this hinged polygon for having a branch. Extrude
twice or thrice at least.

9) In the vertex mode, scale down the top vertices of the
newly-borne branch reasonably.

after extruding Polygon and scaling down Vertices

10) Make one or two branches following the steps 5 – 9. Within
Editable Poly mode go to Subdivision Surface roll-out and check the
option “Use NURMS Subdivision”. Set the Iterations value to 1. You may
have to re-move and/or re-scaling the top, bottom and middle vertices of
the branches. This is up to you.

11) In the Polygon mode, delete the most bottom Polygon of the
Cylinder. And then, hinge 2 or 3 adjacent polygons for having some roots
on the ground. This is also up to you.

after Step 10 and 11

CREATING LEAVES

Setting Geometry for the leaves
——————————–

This is the significant part of my tutorial. So, you are requested to
follow this section precisely as per as possible.

1) On the main toolbar click on the “Snap Toggle” button. Then
right-click on same button to display Grid and Snap dialogues. Uncheck
all option except “Vertex” option. Close the dialogue box.

only Vertex snapping is on

2) Now create 3 spheres each at the top of the three branches while
vertex snapping is on (using one or more non-perspective viewport).
Create another sphere at the top of original trunk as well. Adjust the
radius of these four spheres.

snapping on vertex at the top of the branch

4 spheres have been created

3) Select any of the spheres. Convert it into Editable Mesh. Then in
the Modify panel click Attach List under the Edit Geometry roll-out. In
the Attach List dialogue box select all the remaining Spheres (not the
Cylinder). Then click Attach button. All spheres are now within a single
mesh. Right Click on this Editable Mesh in the viewport and choose
Properties. In the Object Properties dialogue box Uncheck the option
“Renderable” and then click OK.

Spheres are within a single mesh

4) Go to the Create panel. Under the Geometry tab choose Particle
Systems. Click “PCloud” button under the Object Type roll-out. Click &
Drag in the Top Viewport to create a PCloud particle system. Align it
with the bottom of the trunk. While PCloud01 is selected, go to the
Modify panel. And change the parameter as follows :-

(a) Under Basic Parameter roll-out in the Object-Based Emitter group
click Pick Object. Then in a viewport select the Sphere editable mesh.
In the Viewport Display group choose Mesh option.

(b) Expand the Particle Generation roll-out. In the Particle Quality
group choose “Use Total”. Leave the value at 100 for now. You may adjust
it later on. Scroll down and in the Particle Size group set Size value
to 20. You may re-adjust it too later on.

(c) Expand the Particle Type roll-out and set the particles type to
“Facing” in the Standard Particles group.

Creating Material for the Leaves
——————————–

I assume that you are quite familiar with Adobe Photoshop and are able
to use the common features of Photoshop.

1) For the Leaves you must have two pre-made maps. One is Diffuse
and another is Opacity map. It is nice if you have a photograph of a
cluster of leaves (you can get these types of clusters from your own
Photography or the appropriate texture collection). Then take it into
Adobe Photoshop (thanks to the Adobe Company).

2) Erase the area except the Leaves for having a single-color
background (this may be a time-consuming matter). Give the background a
Black color. Save the file as a JPG file for the Diffuse Map using the
“Save As” command of the File Menu.

3) Now select the black background using Magic Wand tool. Then
invert the selection to select the part of Leaves using “Inverse”
command of Select Menu. Give a solid White Color to the selection. Your
Opacity Map is now ready. Save As the file again as a JPG file for your
Opacity Map.

4) Return to Max. Open the Material Editor. In the Material Editor
select the first Material Sample Slot. Set the Diffuse and Opacity Maps
according to the two JPG files you created earlier.

5) Go to the Parent Material. In the Shader Basic Parameters
roll-out, Check “Face Map” and “2-Sided” options. Now, assign the
material to PCloud01.

Material of the leaves

6) If necessary, adjust the “Size” and “Use Total” values of
PCloud01 for a reasonable looking of the tree.

ADDING TEXTURE TO THE TRUNK-BRANCHES AND MAKING GROUND & HEDGE

1) Use a Tree-Bark map for the Trunk-branches. Use a Planner UVW Mapping modifier with the trunk and
set the alignment to Y.

UVW Map setting for the Trunk

2) Add a Plane primitive into the scene using Top Viewport for our
ground. Assign a grass map’s material to the plane.

3) For a Hedge around the tree, create a Tube primitive around the
tree. Make it non-Renderable from its Object Properties (similar as
Step-3 described at /Creating Leaves>Setting Geometry for the Leaves
/section for the Spheres editable mesh). This tube will be used as the
overall bounding shape for our Hedge.

Tube primitive around the tree

4) Make the tube smaller (adjusting Radius 1 & Radius 2 and the
Height) if you think the size is oddly big for a Hedge.

5) Create a PCloud and align it with the Tube. This will be PCloud02
and will be used for our Hedge.

6) Adjust various parameters (following the similar steps as Steps
4(a) to 4(c) described at /Creating Leaves>Setting Geometry for the
Leaves /section for the PCloud01). But, in case of Object-Based Emitter
pick the Tube as Emitter. You may set its size to 7 or 8 and Use Total
value to around 150. Play with several values.

7) Create a material for the Hedge by following similar steps of
those for the Leaves. Use your own maps (appropriate for Hedge). Don’t
forget to Check the options “Face Map” and “2-Sided”.

Assign the material to PCloud02.
RENDERING THE SCENE

1) If wish, you may use a background for the scene. I have used
just a light blue color.

2) Render the Perspective view. Your rendered image should look like
the following image.

Rendered Tree

That’s all for today.