I am interested in finding recommendations on books on writing a raytracer, simple and clear implementations of ray tracing that can be seen on the web, and online resources
Ok, I haven't found any perfect answers myself, that step through from the very basics; I have found a lot of simple ray tracers, and pointers to voluminous textbooks and academic references however.
I haven't tried these ray tracers, but they look interesting and simple.
http://www.barakcohen.co.il/2008/10/ray-tracing-simple-java-open-source.html
http://blogs.msdn.com/lukeh/archive/2007/04/03/a-ray-tracer-in-c-3-0.aspx
http://www.ffconsultancy.com/languages/ray_tracer/
From the ACM Cross Roads student magazine
http://www.acm.org/crossroads/xrds3-4/raytracing.html
This one in C++ is at least short; simplicity was lost for speed
http://ompf.org/ray/sphereflake/
A PhD Thesis on some aspects of ray tracing is here
A series of articles on DevMaster is here
The OMPF forum must read series of posts can be found here
It sounds like the book "An Introduction to Ray Tracing" is what I need ;-), and the authors home page is here for more graphics related programming.
Ray tracing from the ground up includes downloadable ray tracer source code too.
MiniLight is a minimal global illumination renderer.
SmallPT is a global illumination renderer, in 99 lines of C++, with a variant using single precision float on CPU and GPU in OpenCL.
Thanks to the other posters for the pointers