5.8. Tutorial: Creating and Editing Material Maps


Some objects will not appear realistic when displayed in the normal manner as they may have different areas that have different material properties such as transparency and shininess.

In these cases making the whole object appear transparent, shiny or dull is not sufficient.


3DSOM Pro now allows you to create additional material "channels" that allow you to define material properties of the surface on a per-pixel basis.

Starting Point

Create a wireframe and texture map of your object in the usual way.

In our example we captured a model of a transparent bottle by painting it with white paint first. The interior has not been modelled so the bottle is incorrectly closed over at the top. In this tutorial we will show how to enhance the model so that the bottle appears semi-transparent and glossy with the top removed and an opaque non-glossy label will be added to the side.

Figure 5.8.1. Initial example model of painted bottle.
Step 1

If required, make any necessary edits to the texture map using the texture copy and paste tools (see Editing the textures). To summarise we rotate the 3d model in 3DSOM Pro and hit the ID_MODEL_COPYVIEW.jpg Copy View button (or CTRL-C) then paste from the clipboard into a 2D image editing package (e.g. Photoshop). Then using the 2D image editing tools make the required changes. The edited image should then be brought back into 3DSOM Pro by copying onto the clipboard and hitting the ID_MODEL_PASTEVIEW.jpgPaste View button or for Photoshop users flattening the image and dragging the whole image into 3DSOM Pro with the move tool.

In our example, we added a label onto the side of the bottle...

Step 2

If parts of your object are transparent, you will need to create a transparency channel. This is an additional texture map that defines which parts of the object are transparent, semi-transparent or opaque.

From the View Model Window select the Texture Channels > Create New menu item from the Model Tools > Texture Channels menu.

Select the "Transparency" type from the drop-down list. In our case the bottle is predominantly semi-transparent so we selected the "Fill with single colour" option and picked a dark grey colour by clicking the coloured button next to this option.

To create the new transparency channel we select "OK". The new channel will be created and displayed as the texture for the model. You can switch to view the default diffuse channel and back using the Texture Channels > Standard (Diffuse) menu item and Texture Channels > Transparency menu item.

Step 3

To edit the transparency make sure it is selected as the current channel using the Texture Channels > Transparency menu item. Then you can use the standard "Copy/ Paste" editing mechanism to make changes to the texture map for this channel.

In our example we need to paint the label region as white so that it is opaque. To do this we orient the model so we can see the label. To help with the editing we choose to copy the diffuse layer into our editor from this viewpoint - selecting Texture Channels > Standard (Diffuse) menu item then copying and pasting into the image editor.

To edit the transparency channel it is first selected (without changing the model orientation) and then copied to clipboard (CTRL-C) and pasted into the image editor. We then paint the label region to be white...

Figure 5.8.2. Transparency layer edited using a 2D image editor.

The edited 2D image is then pasted back into the 3D model in 3DSOM Pro as before.

Step 4

In our example the bottle is shiny but the label is not. To create this effect we need a "specular" channel which defines the colour of specular highlights across the object.

To do this we select Texture Channels > Create New menu item and select the "Specular colour" type from the drop-down menu. In our example we start with the existing (transparency) channel selecting "copy currently selected map".

We then need to invert the channel so that the white label (from the opaque transparency) is flipped to be black (non-specular). This can be achieved by selecting Texture Channels > Invert channel menu item.

In general you should edit the specular channel so that shiny regions are white and non-shiny regions are black.

Step 5

Finally, to remove the top of the bottle we can create a circular hole by painting a black circle in both the specular and transparency channels (using the "Copy/ Paste" mechanism) to ensure this region is completely invisible.

The final edited material channels for our example appear as follows...

Figure 5.8.3. Edited diffuse channel (left), transparency channel (middle) and specular channel
Step 6

Once the material channels have been created the model can be exported in the normal way.

Screenshots of the final model in an OBJ viewer

Figure 5.8.4. Exported OBJ model - the reverse side of the label is visible through the transparent bottle.
Figure 5.8.5. Another view of the exported model - highlights appear on the bottle but not the label.