Light direction of image in 3ds max- missing attachment here

[nilariver@gmail.com]

Can any body tell how the light direction effect the quality of image? How do we make judgment of this. One of my friend looking to image he will get best out put of the image crisp and clear see the image attched. Can any body tell the logic behind this ? The image which i rendered attaching with this( the completed image with land scape - image 11) The friend's image is only building image (image 1) attached with this. I checked the max file of him nothing special is in rendering settings. The question is how do control the position of light looking the image to get world class rendering output. Please make comment on this

[kippu]

well ...position the sun at wherever the play of shadows brings the best out of the building and observe photography

[kulbir bal]

Try to click the photographs of same building from same angle at interval of 2 hrs and judge the light. then try to find the best light conditions out of them and apply same position in your project

[chiquito]

Try some archiectural photography books. If in need go to some theory behind it. perspective, sun altitude, time of day/year, exposure, bulding receses, bla bla. There was a nice book around that dealt with three point direction light, dont know who the author was, but the concept was interesting in termos of lighting build up, one main light focus and two fill lights.

I doubt you will get any straight foward answer, like "best time is at 14.37hrs in june...".

For renderings, I guess a black shadows doesnt show as much richness as a "trasnparent" shadow. If this is to anser what makes an image better tha another just by lightning. You have to be able see and then to bring up what makes the image a good image.

I like large soft shadows, soft colors. Others like more dark shadows, with stronger burnt light, high contrast. I guess it depens on each one and the effect you are after,and what you can achieve.

If you come across anything interesting, please share.

[Peter M. Gruhn]

My thinking is :

 

Most buildings are (roughly speaking) rectangular with 90 degree corners. Many renderings look better with two facades showing and corners plainly visible; makes them "dynamic" and "interesting".

 

If you put the light directly behind the camera the left facing and right facing sides of the building will be evenly lit, the building will flatten out, the corner will be invisible, the render will look horrible.

 

If the light is off to the side, one face of the building will be brighter than the other. This gives the building volume/form (see definition #17 of 'render') therefore "interest" and "realism".

 

If the light is off to the side, bits that stick out from the primary facade will cast shadows. Everybody "knows" that "shadows add 'interest'".

 

They also help show any surface articulation. This may be particularly important if you are rendering a HUD financed apartment building with minimal volume and surface articulation. "no, there's 4" of foam insulation in stripes every 12' - see how they cast interesting shadows?"

 

http://www.hwb.com/gruhn/portfolio/colored%20elevations.html see here for examples of my shadow treatment (the one in the middle was an attempt to go all GI on the project, to see how I might / how it looked / if it worked... there are all ACAD elevations colored in Photoshop specificly for city submittal as colored elevations, hence the lack of dramatic corner views.

 

http://www.hwb.com/gruhn/portfolio/RARrenders02.html see the one with the red stripes near the top. If you have shallow changes in facade depth, sometimes they just don't show. The grey tower makes the viewer say "why does the red line jog?" the white popout makes the viewer say "so the building gets fatter from here back?" A GI render might bounce some light off the (slender) hidden faces back onto the wall and brighten it up. What I did was insert an omni light scaled very tall and thin with a negative multiplier. This sucked some of the light out from the corner and created just a faint bit of "shadow". And ambient occlusion simulation, just to make the level change discernable. On that pic they could maybe be just a hair stronger, but don't need to be very strong. We aren't trying to show any specific thing "look, there's a shadow here" merely to suggest that something is happening there. The human eye is very good at picking out contrast and exagerating it (read up on "mach banding").

 

A high light can pull shadows down a building which can be useful if you have strong overhangs, especially only partly on a volumetrically articulated building... eg, the setback has a porch roof so the whole setback becomes dark and tells you the form of the larger envelope.

 

But a high light won't cast shadows _across_ a building. Most of the situations I've run across (and that's gigantic sampling ;-)(cough) benefit more from side rather than top light.

 

Also, a lower side light will cast diagonal shadows which, especially against a rectilinear and/or flat facade add more of that "dynamic" "interest".

 

Sometimes a part of the building will project and cast a strong shadow against the main facade - porce, colonnade... these situations are particularly sensitive to light direction. The transition from full shadow to brightly lit can be very narrow. My preference, if possible within the constraints of the rest of the building, is to have part of the back wall in direct light, preferably with a shadow edge across it. Let me see if I have an example...

 

http://www.hwb.com/gruhn/portfolio/RARrenders02.html Back to this page, the one at the very top in tan. The sun comes in, the diagonal says exactly where the edge of the roof is, what part is overhang, what part is set back. Sets off that forward column. This rendering was made because the guy at the city can't read drawings and needed to have a pretty picture to pointout to him how that front entry worked.

 

Actually, that particular image also brings up another thing that light position can do - lie through its teeth. That is the west elevation. Yes, the sun is somewhere around 45 degrees north of west... in Arizona. But, as noted, the purpose of the rendering wasn't to show how the building would look at 10:37 on June 14th, but rather to show some city reviewer what shape the building was.

 

Ah, one more thing comes to mind - light direction has an important effect on the visibility of fine texture (bump maps etc.)

 

Maybe a little OT, a light from low in the back can help things pop from the background and help give them form. The ambient area of an object flattens out (less so with ambient occlusion and various GI effect) and a, I think they're called, rim light can fleshout edges and contour. Less effective, I suspect, on rectilinear materail (you know, "buildings") than on curvy stuff (balls and FOG buildings ;-). Can be particularly effective if the rim light has a contrasting, even strong, hue.

 

http://www.amazon.com/Digital-Lighting-Rendering-Jeremy-Birn/dp/1562059548/ref=sr_1_95?ie=UTF8&s=books&qid=1201934365&sr=1-95 I liked Birn's lighting book.

 

I don't like June because the sun is too high. I like 10am in March. (This, of course, depends on latitude.)