Making a 3D grid in Photoshop

We will start out by creating a grid pattern so open up a new 15 x 15 pixel image. Hit D on your keyboard to reset your colors and use the Paintbucket Tool (G) to fill the image with black. Zoom in on the image by clicking Ctrl Alt + a couple of times until you get a good view.

Change the foreground color to the color you want the grid, I used # 4D5B95.

Alt+click on the the Brush Tool to bring up the Pencil Tool.

Go to the Options bar and set it like this:

Go to Select > All (Ctrl+A) and then to Edit > Define Pattern… Name the pattern Grid in the dialog that appears.

Close this file without saving.

Create a new RGB image with a transparent background, make it big because we are going to crop in later, I used 300 x 300 px.

Go to the Channels palette and hit the -button to create a new channel. Press D on your keyboard so your foreground color is white. Alt+click on the Pencil Tool to switch to the Paintbrush Tool . Go to the Options bar and select a large soft brush, I used Soft Round 65 pixels. Paint some irregular lines on the channel. The white parts will be the high areas and the black parts will be the low.

Go to Select > All (Ctrl+A) and then to Edit > Copy (Ctrl+C). Create a new image with File > New… (Ctrl+N) and hit OK in the dialog without changing any values. Move on to Edit > Paste (Ctrl+V) and save the new image in a suitable location to GridMap.psd. Close the image.

Back to the first image and click the RGB channel and then hit the Layers tab. Grab the Paintbucket Tool (G) and go to the Options bar. Set the Fill to Pattern and choose the Grid pattern we created earlier. Use the Paintbucket Tool to fill the entire layer.

Go to Filter > Distort > Displace… Set the dialog like this:

When you hit OK you will be promted to open a file, select the GridMap.psd you created earlier.

To add depth to the grids we are now going to add some light. Go to Filter > Render > Lighting Effects… Use these setting:

Move on to Edit > Transform > Perspective. Drag one of the top corner nodes slightly towards the middle and drag one of the bottom corner nodes outwards. Hit the -button in the Tool bar.

Go to Edit > Free Transform (Ctrl+T), grab the top center node and pull it down to about the center of the image. Hit the -button

Grab the Crop Tool (C) and drag out the part of the image that you want to keep. When done hit the -button in the Options bar.
Go to the Layers palette and hit the -button to create a new layer. Press D on your keyboard to get black as your foreground color. Alt+click on the Paintbucket Tool to switch to the Gradient Tool.