An environment map lights the model from every direction at once, and it is what a metal reflects. Heimdall3D reads Radiance .hdr and OpenEXR .exr. Save a map into %APPDATA%\Heimdall3D\environments; Add on the environment card opens that folder, and the list is rescanned when you come back.
Ten sources, terms read on each site on 2026-09-09. Four are CC0. One is CC BY-ND. Three are free tiers of commercial libraries that allow use and forbid redistribution. Two are paid. Each entry states the site's own terms and the formats it serves. The site is the authority, and a term can change after the date above.
CC0
1. Poly Haven
polyhaven.com/hdris. 994 HDRIs, 1K to 16K, some at 24K. Served as .hdr and .exr; both open in Heimdall3D.
Licence: CC0 1.0, which asks for nothing. The site's logos, avatars, renders and text are outside the grant.
2. ambientCG
ambientcg.com, by Lennart Demes. 425 HDRI entries, downloaded as zips at 1K, 2K, 4K, 8K, 12K and 16K, with an .exr inside.
Licence: CC0 1.0, sitewide, no stated exceptions.
3. Open HDRI
openhdri.org. 60 unclipped maps of Polish locations, up to 29K, as 32-bit OpenEXR. HDRMAPS links here as its full-resolution freebies.
Licence: CC0, stated on the front page.
4. Giantcowfilms
giantcowfilms.com. A personal library of merged HDRs, three posted, the last in 2018. Check the extension after downloading; the posts state neither resolution nor file format.
Licence: CC0 / public domain, stated by the author on each post.
Free, credit required, no modified copies passed on
5. NoEmotion HDRs
noemotionhdrs.net, by Peter Sanitra and Marek Denko. 150 captures from the Czech and Swiss Alps, about 15000 x 7500 and around 300 MB each, delivered as .rar archives. Heimdall3D opens the file inside if it is .hdr or .exr; the archive's contents were left unchecked for this list.
Licence: CC BY-ND 4.0. Name the authors when you use one. A file you have changed stays with you: NoDerivatives forbids passing on a modified copy.
Free tier, use allowed, redistribution forbidden
6. HDRMAPS
hdrmaps.com, by Grzegorz Wronkowski. Over 150 free maps and a larger paid catalogue; the free tier is around 10000 x 5000. Each product states its own format, .hdr or .exr.
Licence: the site's own. Commercial use and editing are permitted. Resale, repackaging and redistribution are forbidden, and the terms say outright that a file may not be released under an open source licence.
7. HDRI Skies
hdri-skies.com. A sky library with a large catalogue, many free. The free downloads are 2K zips with an .hdr inside; full size is paid.
Licence: the site's own, perpetual and non-transferable. Editing is allowed. Redistribution is forbidden, and so is re-release under Creative Commons.
8. HDRI Hub
hdri-hub.com. A German library with 11 free samples, up to 10240 x 5120, as .hdr.
Licence: the site's own. It binds one user on one workstation. Sub-licensing, resale and redistribution are forbidden, as is inclusion in an open source project or a redistributable template.
Paid
9. Locationtextures
locationtextures.com. Reference and panorama packs for film and games, from $15 a pack, panoramas 30K to 70K. Confirm .hdr or .exr with the seller before buying for Heimdall3D; the product pages state no format.
Licence: the site's own, in tiers, royalty-free. Resale and redistribution are forbidden, and so is bundling with software or an engine.
10. Maxime Roz
maxroz.com, sold through Gumroad. A curated artist library, strong on interiors, with sun-removed variants of many maps. A Free Pack and a paid lifetime Full Pack. Confirm the resolution and .hdr or .exr on the Gumroad product before buying; the site publishes neither.
Licence: the seller's own. The terms live on the Gumroad product page.
Summary
| # | Source | Free | Formats | Licence | Redistribute |
|---|---|---|---|---|---|
| 1 | Poly Haven | yes | .hdr, .exr | CC0 1.0 | yes |
| 2 | ambientCG | yes | .exr | CC0 1.0 | yes |
| 3 | Open HDRI | yes | .exr | CC0 | yes |
| 4 | Giantcowfilms | yes | not stated | CC0 | yes |
| 5 | NoEmotion HDRs | yes | .rar, inner format unchecked | CC BY-ND 4.0 | unmodified only, with credit |
| 6 | HDRMAPS | free tier | .hdr or .exr per product | site's own | no |
| 7 | HDRI Skies | free tier | .hdr | site's own | no |
| 8 | HDRI Hub | 11 samples | .hdr | site's own | no |
| 9 | Locationtextures | paid | not stated | site's own | no |
| 10 | Maxime Roz | free pack, paid full pack | not published | seller's own | see Gumroad |
Formats are as each site states them. A source marked not stated may well serve .hdr or .exr; the page does not say, so this list does not either.