Another lighting model in Octane is HDR / Texture illumination. You need to use pictures taken with a technique called "high dynamic range" in Hdr illumination. It has an "hdr" file extension. Also, you can use any image or procedural texture for the "Texture Illumination". The options are the same. We will expalin our examples through HDR images. You can find out more about HDR on wikipedia. We will not go into details here because it is a well-known topic. Now let's look at the use of Octane HDR / Texture and its options.
ASSIGN HDR/TEXTURE IMAGE
When you define texture or HDR environment from LV, default texture is created according to illumination type to the texture slot. When you select "Texture Environment", automatic "RGB Spectrum" texture is assigned to the Texture Slot. Here you can give it a color or you can use another image or procedural texture. When you select "HDR Environment", an "Image Texture" and "Projection" node with an .hdr extension are automatically assigned to the texture slot. Here you can also define the HDR image you want in the textures slot. Once you have defined the HDR, you can access the "Image texture" settings using the thumbnail arrow next to the texture and change it if necessary. This is the same as the "Image Texture" setting we described earlier in "Using Textures".
USING TRANSFORM OR PROJECTION NODES ON HDR/TEXTURE ENVIRONMENT
You can now access the "Transform" and "Projection" settings according to whether you define the texture or HDR image to "Image texture". In some cases you may want to play both the size and projection settings of your HDR / Texture image. For example, "Sphere Projection" is usually for HDR images. In such scenarios, you can set the HDR / Texture image with both "Transform" and "Projection". We explained these two properties in the chapter "Using Textures".
Main environment Settings
texture and HDR ICONS
With these two icons you can change the environment lighting type to "HDR" or "Texture".
You can adjust the amount of lighting of your HDR. This option is completely dependent on the light values of your HDR image. Some HDRs have a high dynamic range and some have a low dynamic range. In such cases, it may be necessary to change the power setting. Also, if you use Camera Imager with HDR, you can also change scene with Exposure and Gamma settings (We will also explain the "Camera Imager" in the "Using Octane Camera" section). So when HDR is concerned, a lot of factors come into play. Balancing them is the key to a good render.
Info: Keep your HDR image Gamma as 1.
"rot. x" and "rot. y"
This option is for rotating the HDR / Texture image at the "x" and "y" coordinates. You can also do this in other ways. For example, if you define "Projection" in HDR / Texture, you can set the Projection type to "Spherical" and play "R.X", "R.Y" and "R.Z" from "Internal transform". A more practical way is to select the "Sky Object" from the Object manager and use the Rotation tool from the viewport, or from the Coord. Tab witn "R.H" and "R.P".
Enables quicker convergence (noise reduction) for HRDI images by applying importance to certain areas of the HDRI so as to sample rays that resolve to the important areas more often than unimportant areas.
You can also use "Primary environment" and "Visible Environment" for both "HDR/Texture" environments. Go to this section for details.
AO environment texture
AO texture allows you to specify an ambient occlusion texture which will then be used for the AO calculation instead of the environment. In order to use this feature, you need to go to Kernel settings and select "GI_AMBIENT_OCCLUSION" from Directlight. In the following example, hard shadows with "Blue Tint", which is caused by HDR Image, are reduced using AO environment texture. You can use the texture you want as the texture type. In the example RGB spectrum was selected and then gray-white was used.
HDR/TEXTURE MEDIUM settIngs
It is used to give a fog to the HDR/Texture Environments. You can create very nice atmospheric fog because it applies to the scene in general. This fog is not a fake fog but Volume Medium. It interacts directly with any lighting in the scene. Since this topic is wide, we will explain in more detail the "Volumetrics" section.