I this tutorial I will be using Pixplant and a bit of Photoshop in preparing my textures, while VFSU and SketchUp of course for the Vray material.
Step 1: Reference Photo
Here is a reference photo of slate downloaded in this SITE.
Step2: Load the image to Pixplant.
Here is the screen image of loaded texture
This the view of texture tab..
Step 3: Adding Seeds
Click Add Seed from Texture Canvas
Once add seed from texture canvas was clicked a new tab will appear. This tab will have more parameters. Now click Edit Straighten Seed.
A new edit tab will be loaded. This time you need to be aware with the four corner handles.
Step 4: Adjust corner handles.
Like in SketchUp, these handles (pins) can be adjusted. Align these handles as you choose. In the image below I set up the boundary. All the areas outside the boundary edge will be removed.
Here is the straightened Seed texture.
Step 5: Generating materials and textures.
Click 3d Material Tab, here you can adjust Normal, displacement, specular maps.
Screen grab of some adjusted parameters. Notice that there is a real time viewer on the left. Whatever adjustment you do, it will be updated in real-time. You can now save the maps/material textures separately.
Step 6: Adjusting the lightness in Photoshop.
In this image, I used Photoshop to adjust the lightness. This is optional.
Here is the rendered Vray Material.
Download it HERE