How to create free SkyMaps

There are a plethora of ways to create skymaps with varying levels of difficulty and expense. The Terragen program has been mentioned as one way to do so but it is now limited in its use and for commercial purposes is not free. Another program, Bryce, is also not free and seems to of stalled in development based off there only being a 32bit version available. Maybe they are doing things behind the scenes but its still not a free program. This articles intent is to give the JME3 user other options for the creation of skymaps using the free programs Blender and Gimp. It is not the be all, end all of skymap creation. If you know of better methods or tools please feel free to share your wisdom on the forums.

Blender

Using Blender you can create your skymaps for free. Once Blender is setup, your skymaps creation can be done easily. For this article I will go into detail on how to setup Blender to create Angular maps based off a video produced by jMonkey contributor glaucomardano and mentioned in this forum post. Contributor glaucomardano did a good job on the video but it requires previous knowledge of Blender to be able to easily follow along. As such, I will translate it to paper for you. You can view his video by following this link: jMonkeyEngine Tutorial - How to create skymaps using blender.

This tutorial is an adaptation of contributor glaucomardanos production, not an exact duplicate.
These steps assume you’re using the default blender setup and apply to vers 2.78c+.
The tutorial is in checklist format so you can mark items as you go to keep your place.

Angular Map

Open up a web browser and search for "free high res skymap" and select a Angular map of your choice or you can find some here at https://blenderartists.org/forum/showthread.php?24038-Free-high-res-skymaps-%2528Massive-07-update!%2529 instead. Remember to select an ANGULAR map.
Save a map to your pc in a place you can easily locate it from later in blender.

Textures Tab

From the properties panel (bottom-right panel) select the Textures tab (red-white checkerboard) then press the new button to create a new texture. Rename this texture to AngMap.
Under the Image panel select open and navigate to the file you saved earlier.
In the Mapping panel select AngMap from the drop down box.
In the Influence panel de-select blend (ble) and select horizon (hor).

Data Tab

From the properties panel select the Data tab (reel to reel camera).
In the lens panel change the Focal Lens value from 35 to 16. Do this for every camera.

Render Tab

From the properties panel select the Render tab (normal looking camera).
In the Dimensions panel set the resolution to any number that is a power of 2. For this example 1024 x 1024.
Slide the resolution scale to 100%.
In the Output panel change the image type to JPEG. I have found out by trial and error that using a JPEG file has the same image quality as a PNG or DDS file but with a huge difference in image size. A single PNG image will clock in at over 8mb to the JPEG size of 325kb. Even converting to a DDS file comes in at over 3mb for comparison (using RGB888 as is recommended by Momoko_Fan/Core Developer in this forum post) with no gain in image quality that I could see. Your welcome to experiment on your own if you wish.
Set the image format to RGB.
Setting the quality slider has the effect of reducing the image size where 0 is maximum compression and 100 is no compression. In this example, setting it to 0 reduced the image sizes to less than 125kb, once again with no discernible image degradation that I could see.

World Tab

In the properties panel select the World tab.
Check the Real Sky toggle.

Map Generator Setup

From the header at the top of the 3d view click the Choose Screen Layout button next to the word Default and select Split Vertical F/R.
Click the + sign to create a new layout.
Rename this new layout Angular Map Generator or a name of your choosing.
In the left side 3d view, at the bottom, next to the word view, is the Current Editor Type button. Click it and change it to UV/Image Editor.
Place your mouse inside the right side 3d view and press NumPad 5 to toggle ortho view. You’re now setup to render your Angular map.
Save your file.

Rendering And Saving

With your first camera selected (in this case Camera-down) and your mouse inside the right side 3d view, press Ctrl+NumPad 0 to set your selected camera to be the active camera.
Press F12 to render the scene. A image will appear in the left side UV/Image Editor.
With your mouse inside the left side UV/Image Editor you can scroll in or out to center the view.
With your mouse inside the left side UV/Image Editor press F3 to save your image. Rename the image (down.jpg in this case).

Follow this same procedure for the remaining cameras. Rendering, renaming and saving each. After you have rendered all your images you can copy and paste them into your asset folder for JME3. Usually under the Assets/Texture directory.

To use your images in your code, in simpleInitApp(), load the Textures and use the SkyFactory to create your sky.

Texture west = getAssetManager().loadTexture("Textures/Sky/west.jpg");
Texture east = getAssetManager().loadTexture("Textures/Sky/east.jpg");
Texture north = getAssetManager().loadTexture("Textures/Sky/north.jpg");
Texture south = getAssetManager().loadTexture("Textures/Sky/south.jpg");
Texture up = getAssetManager().loadTexture("Textures/Sky/up.jpg");
Texture down = getAssetManager().loadTexture("Textures/Sky/down.jpg");
getRootNode().attachChild(SkyFactory.createSky(getAssetManager(), west, east, north, south, up, down));

Many thanks go out to contributor glaucomardano for his video. He has excellent taste in music.

Listed below are other Blender tutorials JME3 users may find valuable.