This HDRI, together with the included information about the sun's actual bearing and angle during the time of capture, makes it easy to recreate the same lighting conditions as captured in the 3D program of your choice.
The HDRI is unclipped, meaning that the captured dynamic range completely encompasses the light intensities of the environment, for realistic lighting of your scene.
The HDRI is delivered in several different resolutions (all power of 2), namely 1024x512 (1K), 2048x1024 (2K), 4096x2048 (4K), and 8192x4096 (8K). While we recommend to use the highest possible resolution for the final render – to maximize the fidelity of reflections in glossy surfaces – a lower resolution version may be used before the final render, to optimize render times during iterative test renders.
The HDRI has been captured with a white balance of 5400 K, and since this is already accounted for, it should be used in the 3D program of your choice in neutral white 6500 K (RGB 255/255/255), so as not to render it cooler or warmer than captured, unless intentionally so.
There are two paradigms when it comes to setting the exposure during production of HDRIs. One is to manipulate it through normalization, so as to make the light intensity appear balanced out of the box, no matter whether captured in near total darkness or blinding sunlight. This is the usual business in HDRI making, and has the advantage of emitting a fair amount of light directly upon loading the file, without needing special care with regards to camera exposure settings. The disadvantage of this is that such a normalization renders the captured light no longer of photometrically correct intensity – if you change between two normalized HDRIs in the same scene, even if one is supposed to depict a midday environment and the other a twilight environment, the two might appear to light the scene with comparable intensity (although contrast and colour temperature have changed), which intuitively is incorrect.
That is why all of aifosDesign's HDRIs are produced based on the other paradigm, where the exposure is not normalized with regards to display but absolute, and the intensity of the light emitted from the HDRI are precisely as has been captured from the actual light conditions of the environment. While our night-time HDRIs with extreme scarcity of light are anchored to EV 0 so as not to produce rounding errors, all our daytime HDRIs are fixed to the absolute reference point of EV 9 (default EV for Blender, 3DS Max, etc.). This has the advantage that when used with a 3D scene with other light sources, defined with realistic intensity measures (candela, lux, etc.), the whole scene retains its basis on realistic light measures, since the HDRI environment's exposure is not normalized "to look better out of the box". Additionally, it means that when changing HDRIs of this paradigm, you can always expect an HDRI capture of a darker environment to produce a darker light environment for your scene, and vice versa. The disadvantage of this paradigm, which ought to be manageable for most digital artists, is that you will need to adjust the exposure settings for the camera used in the program of your choice, to achieve pleasing levels of light exposure, just as you would do with a real camera.
All aifosDesign's HDRIs are well tested, and each has a recommended EV value for "photographically balanced exposure" (included further down in this product information and in the Read me file), as well as the so called compensation value for balanced exposure that may be used to achieve a balanced exposure of the HDRI's actual light intensity.
The HDRI is supplied in the optimal format Radiance HDR, which does not clip extremely bright light sources (such as the sun) – like OpenEXR 16-bit half float does – nor amasses the bloated file size of OpenEXR 32-bit single-precision float. We are aware that a handful of programs (e.g. Substance Painter – at least prior versions) handle OpenEXR files better than Radiance HDR files, and if your workflow requires it, we are happy to provide any purchaser of the HDRI an OpenEXR equivalent of any desired resolution available – simply generate an invoice from the e-mail delivered to you upon purchase, and attach the invoice to your request, directed towards us via info[at]aifosdesign.se.
Title: HDRI – Winter Slush (Winter, Evening Twilight)
Filename prefix: HDRI_WinterSlush_Winter_EveningTwilight
Keywords: exterior, urban, evening twilight, winter, overcast, natural light, artificial light, low contrast, avenue, Stockholm
Primary light source: Sun
Sun bearing and angle: 232.54 degrees clockwise from North, 1.39 degrees under the horizon
Time of capture: January 20 2021 15:49 (GMT+1)
Location: 59°20'17.47"N 18°6'7.09"E
Photometrically correct exposure value: EV 9
Photographically balanced exposure: EV 6.5
Compensation value for balanced exposure: +2.5
Dynamic range: 12 EVs
White balance (when set to neutral [6500 K]): 5400 K
File format: Radiance HDR (.hdr)
Projection: Equirectangular projection for spherical panorama (360x180 degrees)
Projection center height: 140 cm above ground
Resolutions: 1K, 2K, 4K, 8K
File sizes: 1.64 MB, 6.44 MB, 25.0 MB, 95.5 MB
Backplates included: No
Link to backplates: N/A
Author: Sanning Arkitekter
Copyright: Copyright © 2021 Aifoskela AB
User licence: Royalty-free, non-exclusive, perpetual licence for commercial and non-commercial use
Date of publishing: October 31 2021
More information (file format, resolutions, file sizes, etc.) are found at the bottom of the description.