Nvidia has launched an experimental cubemap/panorama-creation tool called GauGAN360. This is an AI-powered tool that turns your (not so nice) strokes into 360° panoramas that you can use in 3D applications, videogames or interactive products.
Using the tool is pretty simple. GauGAN360 runs inside your browser, and all you need to do is paint on a canvas and click the update button to see the results.
To paint your landscape, you just need to pick among different types of landscape elements from the left toolbar, like rivers, clouds, mountains, suns, etc. You just need to paint what you want, and then, update to see the result. There are three categories to choose from: ground, landscape and plant, so you have a lot of things you can add to your environment.
There is also a dice button above that you can click to randomize a style. Styles are basically the time of the day and weather conditions. For example, this is what I got after I clicked on the dice button, after adding a few things to the landscape.
You can also select a style from the presets above. For example, after clicking the second preset, this is what my image ended looking like.
While you can see the image as either cubemap style or panorama style, I think you can only download the panorama style (I didn’t see any option for cubemap-style downloads). Images are downloaded in JPG format, in very high resolution. On one side, this means you can’t generate HDR images in GauGAN360. On the other hand, these images are very high resolution so they can be used in any way you want (for example, for a background in your architectural visualization) and even use them as source lights for LDR rendering. But if you want to use these as HDRI, keep in mind there are ways to create HDR images using regular images.
Try GauGAN360: http://imaginaire.cc/gaugan360/