Can someone please explain the "Map Size" inside the light properties?

I'm fiddling with some pre-made lights and I notice that some of the Map Sizes are 256 while others are 1024.

Attached Link: excerpt from "This Tutorial" compliments of Dr Geep Studios

A picture is worth ............................ what you pay for it, no?

cheers,
dr geep
;=]

If its the shadow map value it controls the resolution of the shadow. Things like Nostil glow can be inadequate shadow resolution. You can reduce the value if you zoom in the shadowcam  to cover only the scene area seen by the camera .

Great pics Dr Geep.

Thanks! That makes perfect sense!   So now I know that for the particular image that I'm working on, I can decrease the map of that shadow down to 256 because it doesn't matter if there are jaggies. Any shadow from that light will be in a darker area and mostly off screen!

Thank you Mark.

In case it's not obvious to everyone reading this, I just thought I'd mention that map size is only relevant if you are using Depth Map shadows.
:O)

Attached Link: http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2767631&page=3#message_3425286

Thanks! I'm adding this thread and the one to Raven's post, to the Lighting Bookmarks Thread.

Don't overlook the light's ShadowCam's effect on all this.

Bear in mind that simply zooming-in a light's ShadowCam will have the same effect as increasing the ShadowMap Size, - i.e. increasing the shadow's resolution, - without increasing the render time required when using the larger ShadowMap size.

...consequently zooming the ShadowCam in, while reducing the ShadowMap size, can speed up the renders while retaining the same shadow sharpness.  The ShadowCam's field of view generally ends up generating shadows in areas not actually in your rendering camera's field of view.    (zooming in alone doesn't reduce the render time, just the smaller ShadowMap size)

acadia after working so many years with poser you didnt know what the shadow map does? 

Quote - acadia after working so many years with poser you didnt know what the shadow map does? 

Not until now I didn't :) I never explored that aspect of lighting before.  

Lots & lots of interesting nooks & crannies now-a-days.   Wez all still be a learnin!

Quote - > Quote - acadia after working so many years with poser you didnt know what the shadow map does? 

Not until now I didn't :) I never explored that aspect of lighting before.  

you know i just dont belive this. that you rendred 100 of renders and never changed the shadows.

i dont to belive this :) 

Thank you for asking this question Acadia, I am wrestling with the lighting myself and was wondering about this very thing.

Quote - In case it's not obvious to everyone reading this, I just thought I'd mention that map size is only relevant if you are using Depth Map shadows.
:O)

Oh! I only use ray-traced shadows anymore. Jeez, I really don't understand this whole lighting thing, no matter how much I read. I followed that whole tutorial of BagginsBill on getting rid of nostril-glow and he was using depth-mapped shadows, and it was such a long time ago (old thread) and later on in the thread come to find out he rarely uses depth-mapped shadows anymore, only ray-traced. So, all those shadow-cam exercises were for naught. Now, you're saying I can use 256 map size for my renders and it won't matter? What about the detail in the image itself (not the shadow, but the rest)?
Plus, raytraced shadows would be clearer (higher detail, lessening jaggies) with a higher map size, wouldn't they? Or am I missing something?

RV: raytraced shadows do not use maps at all. The shadows are generated by following each raytrace out from the camera through the imaginary render pixel plane, and calculating the light received at each point that the ray 'hits', plus any additional effects from recursive raytrace bounces due to refraction, reflection, fresnel, or gather. Plus AO of course.

So for example, if a raytrace points to a surface which is partially lit by one or more lights and partially in shadow, the raytrace will hit the object, and 'look' in the direction of each light to see how much illumination it is receiving from it. If there is something in the way, it receives no (or less) light, and if there is nothing in the way it receives more light, and it calculates the appearance of the rendered pixel using that information.

As you know, depth map shadows are calculated for each light before the actual render begins, and stored in memory as a data map showing how much each light illuminates each point (within the field of view that is covered by its associated shadowcam). This makes the render itself quicker, and also these memorised shadow maps can be re-used for subsequent renders, making things quicker still.