minning.de - Stefan Minning: CG Artist and Developer

This lens shader is designed to be phys­i­cally accu­rate and mim­ics a DSLR camera’s expo­sure set­tings. For simplicity’s sake I mod­eled the set­tings after the pop­u­lar and beginner-​​friendly Nikon D40.

Phys­i­cal­Cam­era bases its expo­sure cal­cu­la­tions on these real-​​world cam­era units:

• Film speed (ISO)
• Shut­ter speed
• Aper­ture (f-​​stop)
• White bal­ance

The shader offers use­ful pre­sets for each indi­vid­ual set­ting and also com­bined pre­sets for var­i­ous light­ing sit­u­a­tions such as sun­light, over­cast skies, tung­sten etc. as you might know them from your DSLR cam­era.
Any­one famil­iar with pho­to­graphic cam­eras will find Phys­i­cal­Cam­era intu­itive to use.

More­over, Phys­i­cal­Cam­era fea­tures basic color cor­rec­tion set­tings and sim­u­lates var­i­ous pho­to­graphic effects includ­ing vignetting, chro­matic aber­ra­tion and film grain for added realism.

Usage

This shader can be used as a basic tone map­ping oper­a­tor and to prop­erly expose an image as you would with a real DSLR camera.

Phys­i­cal­Cam­era is designed for best results when used in com­bi­na­tion with Phys­i­cal­Light and Phys­i­cal­Ma­te­r­ial.

Phys­i­cal­Ma­te­r­ial is designed to accu­rately sim­u­late real-​​world mate­ri­als in a real­is­tic and effi­cient shad­ing model.

This men­tal ray shader is based on Maxwell’s mate­r­ial sys­tem and offers very few options com­pared to men­tal ray’s archi­tec­tural mate­ri­als by expos­ing only the most nec­es­sary shad­ing para­me­ters and inter­nally adjust­ing oth­ers auto­mat­i­cally in order to main­tain phys­i­cally plau­si­ble values:

• Reflec­tion 0
• Reflec­tion 90
• Index of refraction
• Rough­ness
• Bump

But even with these few options it is pos­si­ble to cre­ate just about any (hard) sur­face mate­r­ial you could imag­ine, thanks to the shader’s built-​​in lay­er­ing sys­tem. And since the shader is energy con­serv­ing it is really sim­ple to cre­ate pho­to­re­al­is­tic shad­ing, espe­cially when used in com­bi­na­tion with my Phys­i­cal­Light.

Of course it is also pos­si­ble to get “under the hood” and tweak advanced fea­tures such as Final Gather con­tri­bu­tion and ambi­ent occlu­sion, but the shader is designed to let you ignore those for the most part… the pre­sets pretty much sim­u­late the mate­r­ial they say they will with­out much ado.

The shader fea­tures spec­u­lar high­lights based on Lafortune’s model, glossy reflec­tions and an inte­grated lay­er­ing sys­tem that lets you cre­ate iri­des­cent coat­ings and advanced effects such as greasy spec­u­lar highlights.

Usage

Phys­i­cal­Ma­te­r­ial is best suited for met­als, plas­tics, car paint, clay, wood, stone… basi­cally any type of hard mate­r­ial. The shader comes with a num­ber of pre­sets that sim­u­late real world mate­ri­als for quick setup in archi­tec­tural renders.

Phys­i­cal­Tones is a true tone map­ping oper­a­tor for men­tal ray. As you can see from the sam­ples, tone map­ping can be used for var­i­ous effects — real­is­tic and artis­tic.

But the mia_​exposure nodes already do tone map­ping, you might say! Well… not exactly. Not in the true sense of the word, any­way.
What they do is in real­ity just glo­ri­fied gamma cor­rec­tion which works on indi­vid­ual pix­els. Tone map­ping on the other hand is specif­i­cally designed to bring high dynamic range (HDR) images into a more lim­ited dynamic range and works with indi­vid­ual pix­els as well as spa­tial sam­pling depend­ing on the algo­rithm used.

Usage

Tone-​​mapping is the process of bring­ing high dynamic range images into a range more suit­able for dis­play on ordi­nary com­puter mon­i­tors.
Phys­i­cal­Tones can be used in com­bi­na­tion or as a replace­ment for mia_​exposure_​photographic, mia_​exposure_​simple and Phys­i­cal­Cam­era. The shader often does a bet­ter job at lim­it­ing the dynamic range or can be used to achieve the trendy HDR photo look.