HDR , Dds , Env files

[syntheticmagus]

Hi Propido,

Welcome to Babylon! As this is about 3D modeling/export, I’ll have to call for help from subject matter experts @PatrickRyan and/or @Drigax for part of it, but I can at least answer some of you’re asking.

1. .hdr is (apparently) a lossless image format for storing high dynamic range image data; I’m no expert, but I’m guessing that the focus of is on quality as opposed to compression, meaning it’s likely good for source content but not as ideal for shipping over a network to be displayed in real-time. .dds is a DirectDraw Surface; this format is designed specifically for use in real-time rendering, but it’s a Microsoft-specific type that can be tricky to use outside of the Windows ecosystem. .env is, as I understand it, a file type introduced by Babylon as a more Web-friendly alternative to .dds; a more precise description is in the second paragraph of the documentation section I linked to, but it’s basically just a pre-mipped cube map of PNGs along with a little bit of metadata.
2. As alluded to above, it depends on the use case. If you’re trying to store high-quality image data you’ve captured so you can make use of it later, you probably want to keep that in .hdr. If you’re working with Windows-focused game dev tools and want to use your texture specifically in a real-time Windows native application, .dds is probably the canonical choice. However, if you want to use your texture in a Babylon.js app that will be retrieved from the Web and run on a variety of devices/platforms, I think .env is probably your best choice.
3. Creating .envs is covered in a different section of the documentation you read: Creating a compressed environment texture. That workflow will allow you to go from .dds to .env. Going from .hdr to .dds is a separate step, and either PatrickRyan or Drigax will probably know more specifics than I do, but broadly speaking you just need a tool that can import .hdr and export .dds. A quick glance around the Internet indicates that there are plugins to make Photoshop do this, and that GIMP might be another option. Also, if you search for, “convert hdr to dds,” there are quite a lot of sites that claim to be able to do this for free.

Hope this at least helps you get started!