Light and shadow

[ldexl]

Hi, I have a little problem during rendering interior of apartment. I am using Auto Cad 2009 and I have trouble with shadow and light. In realistic view, when I turn on the sunlight, inside of apartment iz visible only the part of the room on which the sunlight is falling through the windows, and I can't make the rest of the room visible as it should be during the day. Here are the pictures. First is without shadow and light, second is with shadow and light, and on the third is additionally turned on background sky.

 

 

 

Any kind of help would be appreciated

 

 

 

 

 

[Cad64]

Try enabling global illumination: http://www.cad-notes.com/2010/07/setting-up-autocad-sun-light-is-easy/#sthash.uZutvcM6.dpbs

[tzframpton]

A couple things to reference:

 

Render Exposure:

http://www.cadtutor.net/forum/showthread.php?56138-Render-Exposure-Settings

 

Quick Tip Render Settings:

http://www.cadtutor.net/forum/showthread.php?35688-3D-AutoCAD-Render-Tip-Quick-settings-with-great-results

 

*EDIT*

Both my posts are actually covered in Cad64's single link... a little redundant but hey....

[ldexl]

Hi.

 

Thanks a lot to both of you, those are helpful tutorials. But still i have few problems. When i set the camera view and i turn on the sunlight, i cant turn on sky properties i can turn it only if i add additional light somewhere in dwg. And when i need to adjust rendering exposure i cant because the option is frozen. The same problem is with sky properties, option is frozen, when i put some additional light option is available. So i tried the tutorial on some other dwg. And its working. For this dwg i have other question. I made two pictures picture on the righr is only with shadow light and sky background and the other is with additional modification as it was explained in tutorial. So my question is, is it possible to adjust properties so gras could be visible as it is on the other picture.

 

And does anyone know what is this happening with this two options in first dwg

 

[tzframpton]

My first guess as to why these options are disabled is because you don't have your LIGHTINGUNITS set to 1 or 2, which enables Photometric Lights. Read here:

http://exchange.autodesk.com/autocad/enu/online-help/search#WS1a9193826455f5ff85ce5a10defe5d82a-7ef7.htm

 

If you change your LIGHTINGUNITS to 1 or 2 (preferably 2) then you've enabled photometric lighting, which is what makes realistic renderings possible. In a nutshell, it replicates the "physics" of light, which is critical in realistic renders because in reality, optics from our eyes and camera lenses are simply capturing light that is illuminating off objects. You can get a quick and general description of lighting in AutoCAD here:

http://exchange.autodesk.com/autocad/enu/online-help/search#WS1a9193826455f5ffa23ce210c4a30acaf-7d49.htm

 

And general info on photometry here:

http://en.wikipedia.org/wiki/Photometry_(optics)

 

It's also good to learn about attenuation when placing lights, which can be studied here with the inverse-square law:

http://en.wikipedia.org/wiki/Inverse-square_law

 

Hope this helps.

[ldexl]

Thank You StykFaCe

 

links you posted helped me improve my rendered image, but still I have some difficulties, for next image I change some properties so the grass could be visible, but now I have other problem as You can see on the image now the corners are brighter then the other parts of the room

 

I started working in 3D about an year ago and I know that I'm probably bothering you with silly questions but i can't find the solution for this problem.

 

I was experimenting with properties, so here is the result which i think is better then the last one but still it's not what I want

 

 

here are the properties that i set up for this image

LIGHTINGUNITS: 2

PRESENTATION MODE

GLOBAL ILLUMINATIONS: 2

PHOTONS: 1

RADIUS MODE: on

RADIUS: 3000

FINAL GATHER: on

ENERGY MULTIPLIER: 6

 

what can I do to remove bright corners?

[tzframpton]

You don't have enough photons calculating the light.

• Under Ray Tracing, turn them all up to around 20 minimum.
  
• Photons/sample: turn up to 5,000.
  
• Max Depth/Reflections/Refractions turn up to 20 minimum.
  
• Under Final Gather, turn Rays up to 10,000.
  

Also I notice your shadows are ray traced and not soft. Under "Shadows", set "Shadow Map" to ON and Mode to Segmented, then set the multiplier to 2.

 

Try those settings and post back your results.

[ldexl]

thank You, here is what i accomplish so far, I enter all the values that you suggested and when the render was completed the image turn out black, so I started to combining diferent values, I didn't try all available options but so far I have better result than the last time

 

here are the values that I enter for the image below

 

PRESENTATION MODE: on

GLOBAL ILLUMINATION: on

- PHOTONS/SAMPLE: 5000

- USE RADIUS: on

- RADIUS: 4500

- MAX DEPTH: 20

- MAX REFLECTION: 20

- MAX REFRACTION: 20

FINAL GATHER: on

- RAYS: 1000

LIGHT PROPERTIES:

- ENERGY MULTIPLIER: 12

 

 

I'll try couple things over the weekend, so the room could be a little brighter and I'll post the results here

[spittle]

Did you get the exposure control working?

 

I think you need to expose correctly for the interior - which will always blow out the exterior unless you come up with a non-physical lighting setup i.e. make the exterior less bright and increase the overall exposure. With a default daylight system the sun is always going to be too bright if you want to see the interior and the grass.

 

It works more or less like regular photography.

[ldexl]

I am sorry because it takes me to long to answer your replies, it is because I have some problem with computer, so I can't work . I hope that the problem will be fixed in the next couple of days so I can try things that you suggested