Jelmer
11-26-2005, 01:40 PM
i decided to make a little tutorial for all you guys at cgtalk, it's my first tutorial so don't be too harsh on me if you don't like it:D , you need some basic max skills (but not much), this tutorial was made in max 7 but you can probably do it to in version 6 or higher.
It's just a basic tutorial but it's quite usefull I hope, explaining the basics of mental ray, area lights and GI(global illumination)
GI is one of the most important elements in mental ray( i think) to create a realistic render, 'rays' of light( called photons) are emmited from the light and bounce on objects in your scene, the photons illuminate your scene, it's not 100% realistic but it's similar to real light.
Area lights can be used to create softer shadows, you often see soft shadows on cloudy days, so you shouldn't use them if you want to simulate a blue sky and a bright sunny day, because shadows are usually hard then.
enough talking, let's start with the tutorial!
First we're going to create the scene, it's very simple because we just want to focus on lighting in this tutorial!
here's a basic picture of the whole scene:
http://img395.imageshack.us/img395/319/tutorialscenefile20ix.th.jpg (http://img395.imageshack.us/my.php?image=tutorialscenefile20ix.jpg)[/url]
1.create a ground plane, 300x300 and set the render scale to 1000 (so the plane is very big when you render it)
2.create a sphere,(on top of the ground plane) i used a radius of 15 cm.
3.navigate your perspective view until you have a good view of the sphere, now press ctrl+c, this will create a new camera from this view, change your perspective view to camera1
4.create a big sphere around your scene, right click>convert to editable poly, go to the modifiy tab, press 4 (to go into poly subobject mode) select all the polys, go to the edit polygons tab, and press the flip button. We're doing this because we want the polygons to bounce towards the scene, if we didn't create the sphere the render time would be longer because the photons wouldn't bounce back into the scene.
5. press ctrl+a (to select all), press M,(material editor) and then press the assign material to selection button when you have a default material selected, now all the objects have a standard grey material.
6. now the most important object, the light, to keep it simple we're using only one light.
Create an mental ray area omni somewhere in the scene, and then use these settings:
explaination on settings:
area light:
-Radius: the size of the light, bigger radius = softer shadows
-samples: many samples= high quality+render time
-GI settings: energy= more energy = lighter scene, longer render time, tweak the settings to see the results!
decay= how fast the photons lose energy
caustic photons= creates caustics, maybe we'll use it in another tutorial!
GI photons= very important, how many GI photons the light emits, scroll down to see the results of tweaking this setting \/
[url="http://img506.imageshack.us/my.php?image=lightsettings26pq.jpg"]http://img506.imageshack.us/img506/295/lightsettings26pq.th.jpg (http://img464.imageshack.us/my.php?image=tutorialscenefile8cj.jpg)
7. press f10 to open the render panel, and use the settings in this picture:
http://img464.imageshack.us/img464/1204/rendersettings5ye.th.jpg (http://img464.imageshack.us/my.php?image=rendersettings5ye.jpg)
8. here i've made some adjustments to the settings and you can see the result, you can further tweak them yourself!! use more photons or more samples etc. but remember that the render time will increase too!
different settings+renders:
http://img381.imageshack.us/img381/8490/differentsettings7sc.jpg (http://imageshack.us/)
cylindrical type area light: because the light is a longer shape the shadows will be softer in one direction, because it's a cylinder shape you also need to select the height.
i hope you enjoyed this tutorial, if you have any questions or comments about the tutorial you can post them here or e-mail me, jelmer_b4@hotmail.com
It's just a basic tutorial but it's quite usefull I hope, explaining the basics of mental ray, area lights and GI(global illumination)
GI is one of the most important elements in mental ray( i think) to create a realistic render, 'rays' of light( called photons) are emmited from the light and bounce on objects in your scene, the photons illuminate your scene, it's not 100% realistic but it's similar to real light.
Area lights can be used to create softer shadows, you often see soft shadows on cloudy days, so you shouldn't use them if you want to simulate a blue sky and a bright sunny day, because shadows are usually hard then.
enough talking, let's start with the tutorial!
First we're going to create the scene, it's very simple because we just want to focus on lighting in this tutorial!
here's a basic picture of the whole scene:
http://img395.imageshack.us/img395/319/tutorialscenefile20ix.th.jpg (http://img395.imageshack.us/my.php?image=tutorialscenefile20ix.jpg)[/url]
1.create a ground plane, 300x300 and set the render scale to 1000 (so the plane is very big when you render it)
2.create a sphere,(on top of the ground plane) i used a radius of 15 cm.
3.navigate your perspective view until you have a good view of the sphere, now press ctrl+c, this will create a new camera from this view, change your perspective view to camera1
4.create a big sphere around your scene, right click>convert to editable poly, go to the modifiy tab, press 4 (to go into poly subobject mode) select all the polys, go to the edit polygons tab, and press the flip button. We're doing this because we want the polygons to bounce towards the scene, if we didn't create the sphere the render time would be longer because the photons wouldn't bounce back into the scene.
5. press ctrl+a (to select all), press M,(material editor) and then press the assign material to selection button when you have a default material selected, now all the objects have a standard grey material.
6. now the most important object, the light, to keep it simple we're using only one light.
Create an mental ray area omni somewhere in the scene, and then use these settings:
explaination on settings:
area light:
-Radius: the size of the light, bigger radius = softer shadows
-samples: many samples= high quality+render time
-GI settings: energy= more energy = lighter scene, longer render time, tweak the settings to see the results!
decay= how fast the photons lose energy
caustic photons= creates caustics, maybe we'll use it in another tutorial!
GI photons= very important, how many GI photons the light emits, scroll down to see the results of tweaking this setting \/
[url="http://img506.imageshack.us/my.php?image=lightsettings26pq.jpg"]http://img506.imageshack.us/img506/295/lightsettings26pq.th.jpg (http://img464.imageshack.us/my.php?image=tutorialscenefile8cj.jpg)
7. press f10 to open the render panel, and use the settings in this picture:
http://img464.imageshack.us/img464/1204/rendersettings5ye.th.jpg (http://img464.imageshack.us/my.php?image=rendersettings5ye.jpg)
8. here i've made some adjustments to the settings and you can see the result, you can further tweak them yourself!! use more photons or more samples etc. but remember that the render time will increase too!
different settings+renders:
http://img381.imageshack.us/img381/8490/differentsettings7sc.jpg (http://imageshack.us/)
cylindrical type area light: because the light is a longer shape the shadows will be softer in one direction, because it's a cylinder shape you also need to select the height.
i hope you enjoyed this tutorial, if you have any questions or comments about the tutorial you can post them here or e-mail me, jelmer_b4@hotmail.com