By Dennis Collin
Achieving realistic day light scenes in 3ds Max can be a challenge. But knowing some magic numbers and settings can get a user a long way towards a good and credible output without too much 'fiddling around'. Especially with Mental Ray (mr) which can seem a little daunting to the new Max user.
Lighting is one of the concepts I go into much more detail on a typical Cadline 3ds Max Course. But if we consider the following scene that is sourced from Sybex Max Essentials Courseware that we use.
The model uses an mr Daylight System, with mr Sky environment. With an environment exposure setting of around 12 and the scene using Arch and Design Materials. These materials give the best results with reflections and indirect lighting calculations with the mr renderer.
Day time Scene, Using MR Daylight System, EV setting of '12'
To achieve an internal night time scene, we obviously don't need the sun so the sun can be turned off. Although I have found leaving the Skylight system on at a greatly reduced magnitude can help simulate 'star light' rather than the pure black default sky. For the example below the skylight won’t be noticeable but for a night time exterior scene it would make a considerable difference. Try multiplier values like 0.001 and go from there.
NIght time Scene, Using MR Photometric Lights, Free Light 130 Candela brightness, EV setting '4.0'
It is worth noting the default intensity for Photometric lights is about 10 times too bright, which results in an over lit scene and as a result users tend to adjust other parameters like Exposure Value (EV) and units to compensate. Remember Units influence how light attenuates in Max... so for most internal modelling purposes Units should probably be millimetres especially if importing Revit models. If in doubt take measurements of known elements. Remember we always model at 1:1 scale (even for visualisation purposes, size matters!) Also check the unit settings in the file itself, the Americans tend to work in Inches (which will impact the amount of light spread around the scene)
In reality the best strategy is to get the lights to emulate real world lighting fittings. Editing the lighting brightness settings to about 120-150 candela or around 400 lumens will mean you don't have to over correct settings like 'EV' elsewhere. If you aren't too familiar with lighting units, then consider using the photo metric lighting templates included in 3ds Max which state a 100 watt bulb as 139 candelas.
The Environment dialogue box is instrumental in changing many of the scene's lighting settings.
Another thing to remember is to use the Render Preview in the environment dialogue before doing a 'full' render. So much time can easily be spent needlessly rendering under lit or over lit scenes. Or alternatively consider using the render region function from the render frame window.
An interesting development with the advent of Max 2016 is the potential of rendering in the Cloud, which will be useful in saving time, but it is useful to remember you will be charged in Cloud credits for each render job, so there's a lot to be said in getting it right first time!
If you are just embarking on using Max to create interesting and compelling visualisations do check out another blog where I provide some useful keyboard shortcuts and tricks which perhaps compliments what has been said in this document.
Whilst there is no substitute for attending a 3ds Max course, these documents should prove useful 'aide memoires' post training along with blogs and other whitepapers and documents provided on the Cadline Community.