I am pleased to announce the first PDF edition of Rendering with Radiance. It is a USD$7 (+VAT or sales tax if you live in Washington state) no-DRM download, available at Gumroad at Rendering with Radiance v1.1 (PDF). (No shipping charges! Yay!) If you buy it, please leave a star rating so that the book will become easier to find on Gumroad.
The PDF is optimized for display, not printing. This is the fourth “printing,” which I am calling v1.1 - a conventional publisher might be tempted to call it a second edition, but the changes are small. It is still mostly the same book we have all come to know and love, but there have been some updates to bring it into the 21ˢᵗ century - command names have been updated and the hdr file extension has been adopted throughout the book.
I still have a few physical copies of the third printing available for the usual price of USD$35, and a few misprints available for USD$5 (the printer left out the math symbols, making hash of the theory chapters towards the end of the book, but you can still use these to learn Radiance.) These remain available for those prices + shipping, if there is interest.