Sunday, February 6, 2011

1

MRDS: HOW TO ADD YOUR CUSTOM SIMULATED OBJECTS (AND DON'T DIE ON THE ATTEMPT)

As you might know, the simulator integrated in Microsoft Robotics Developer Studio can import 3D objects into your simulated world. The most common format used to import those objects is ".obj", it is a simple format that most 3D Design Programs can export to.

For the project that I am working right now it was needed to insert a realistic 3D model of a human face into the simulation.  The model of the 3D face was stored in 2 different sets of files:

Head 1.obj
Head 1.mtl
Head 1.bmp

Eyeballs 1.obj
Eyeballs 1.mtl
Eyeballs 1.bmp

The first set of files corresponds to the model of the head and the second set corresponds to the model of the eyes. The .obj files define the geometry of the objects, the .mtl define the properties of the materials of the objects and the .bmp is the texture.

So, first lets try to insert the head. The source code would look like this, add it to the definition of the simulated world:

//Insert the head 
SingleShapeEntity head =
 new SingleShapeEntity(
  new SphereShape(
   new SphereShapeProperties(
    0,
    new Pose(),
    0.1f)),
  new Vector3(0.0f, 0.5f, -2f));
head.State.Assets.Mesh = "Head 1.obj";
head.SphereShape.SphereState.Material = new MaterialProperties("sphereMaterial", 0.5f, 0.4f, 0.5f);
head.State.Name = "Head";

SimulationEngine.GlobalInstancePort.Insert(head);
 


Ok, now compile and execute the simulation:


Uhmmm... WHERE IS MY HEAD? Ok, don't panic! Let's try to find if it is out there. Select the "edit mode" on the simulator window:


Well, it looks like the head is inserted in the simulation, but for some esoteric reason we are not able to see it. Lets look around and try to find it. Use the mouse to rotate the camera in the simulated environment.


Did you see that?


There is some vertices there... wait a minute! Lets move the camera away about 20 meters.


There it is!! But it is a huge head!! No problem... just resize it. To do that, just add the proper line of code before inserting the object into the Simulation Engine:

head.MeshScale = new Vector3(0.01f, 0.01f, 0.01f);



Great, but, where is the texture? mmm thats odd. Why is it not showing the texture?

If you open the File "Head 1.obj" you will see something like this:

# 3ds Max Wavefront OBJ Exporter v0.97b - (c)2007 guruware
# File Created: 30.01.2011 20:28:48

mtllib Head 1.mtl

...

In the .obj file there is a reference to "Head 1.mtl", I'd bet having spaces in the file name would freak out MRDS , well... let's open that file in a text editor:

# 3ds Max Wavefront OBJ Exporter v0.97b - (c)2007 guruware
# File Created: 30.01.2011 20:28:48

newmtl defaultMat
 Ns 30.0000
 Ni 1.5000
 d 1.0000
 Tr 0.0000
 Tf 1.0000 1.0000 1.0000 
 illum 2
 Ka 0.5500 0.5500 0.5500
 Kd 0.5500 0.5500 0.5500
 Ks 0.0000 0.0000 0.0000
 Ke 0.0000 0.0000 0.0000
 map_Ka C:\Users\sama-sama\Desktop\Head 1\Head 1.bmp
 map_Kd C:\Users\sama-sama\Desktop\Head 1\Head 1.bmp

mmm Interesting, the file "Head 1.mtl" has an absolute path reference to the file "Head 1.bmp" (that, by the way, doesn't even exist in my computer, it is a path on the computer of the designer that modeled the head.Thanks a lot 3ds Max Studio). Let's try something: Remove the spaces in the file names and get rid of the absolute paths.

Now the files should be named as:

Head1.obj
Head1.mtl
Head1.bmp

Eyeballs1.obj
Eyeballs1.mtl
Eyeballs1.bmp

Now the content of Head1.obj should look like:

# 3ds Max Wavefront OBJ Exporter v0.97b - (c)2007 guruware
# File Created: 30.01.2011 20:28:48

mtllib Head1.mtl

...

And the content of Head1.mtl should be like:

# 3ds Max Wavefront OBJ Exporter v0.97b - (c)2007 guruware
# File Created: 30.01.2011 20:28:48

newmtl defaultMat
 Ns 30.0000
 Ni 1.5000
 d 1.0000
 Tr 0.0000
 Tf 1.0000 1.0000 1.0000 
 illum 2
 Ka 0.5500 0.5500 0.5500
 Kd 0.5500 0.5500 0.5500
 Ks 0.0000 0.0000 0.0000
 Ke 0.0000 0.0000 0.0000
 map_Ka Head1.bmp
 map_Kd Head1.bmp

Save the changes to all the files, and execute again:


Yeah! Much better!! Now we only have to do the same changes in the files corresponding to the eyes and insert them into the simulation, the final source code would be:

//Insert the head 
SingleShapeEntity head =
 new SingleShapeEntity(
  new SphereShape(
   new SphereShapeProperties(
    0,
    new Pose(),
    0.1f)),
  new Vector3(0.0f, 0.5f, -2f));
head.State.Assets.Mesh = "Head1.obj";
head.SphereShape.SphereState.Material = new MaterialProperties("sphereMaterial", 0.5f, 0.4f, 0.5f);
head.State.Name = "Head";
head.MeshScale = new Vector3(0.01f, 0.01f, 0.01f);
SimulationEngine.GlobalInstancePort.Insert(head);
 
SingleShapeEntity eyeballs =
 new SingleShapeEntity(
  new SphereShape(
   new SphereShapeProperties(
    0,
    new Pose(),
    0.01f)),
  new Vector3(0.0f, 0.5f, -2f));
eyeballs.State.Assets.Mesh = "eyeballs1.obj";
eyeballs.SphereShape.SphereState.Material = new MaterialProperties("sphereMaterial", 0.5f, 0.4f, 0.5f);
eyeballs.State.Name = "Eyeballs";
eyeballs.MeshScale = new Vector3(0.01f, 0.01f, 0.01f);
SimulationEngine.GlobalInstancePort.Insert(eyeballs);


Let me introduce you to Mary:




I would like to specially thank Sama-Sama Studio for providing several realistic head models for the experiments of my project.

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