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Do Daz Studio point lights really follow the Inverse square law?

SzarkSzark Posts: 10,634
edited December 1969 in Daz Studio Discussion

I was always under the impression they didn't. I know the distance of light cast is dependent on Intensity but I never realised if followed this law.

Comments

  • SzarkSzark Posts: 10,634
    edited December 1969

    Is there somewhere I can go and check these facts I find without the need to ask here?

  • Richard HaseltineRichard Haseltine Posts: 102,252
    edited December 1969

    Yes, point lights are inverse square. They are the only default lights that do obey physics - the spots don't have any fall off, and the new linear point lights are linear or use a start/end distance.

  • SzarkSzark Posts: 10,634
    edited December 1969

    Thanks Richard. Now please don't take this the worng way but how can I find these answers myself, not that I don't trust what you say becasue you seem to know a lot about this that is not even documented so I do trust what you say. When you are not sure you say so. It is just a case of who do I believe, years of seeing contradicting info or go with my gut and trust one person. What peeves me off a little as no one bothered to correct me in my Point Light tutorial. I'd better corect that at some stage too.

    Oh this is just for the normal point light, I know my info is correct on the other lights in DS. ;)

  • SimonJMSimonJM Posts: 5,997
    edited December 1969

    A small correction then ... the distance light travels/is cast is not based on it's intensity. What is dependant on intensity is how bright the illumination it casts is once it gets there (see inverse square law!) Some light from a candle would make it to a wall 20 miles away (maybe just a photon or two ..) just as that from a search light would (but a few more photons with a bit more energy and thus more noticeable).

  • SzarkSzark Posts: 10,634
    edited December 1969

    Thanks Simon yes indeed http://www.daz3d.com/forums/discussion/29667/ but crudely put it in real simple terms Increasing the intensity of a point light does cast a wider and brighter spread of light. I think this is when a lot of newcomers get put off with jargon and math get thrown at them without an simplified explantion what it means in real terms when dealing with certain lights in the CGI world. But what you say is true light just keeps on travelling. Do you mind if I use that Simon as it would make for a good intro to the inverse sq law, then if folks want to know more they can go and research this law when or if they feel like it on their own.

  • Richard HaseltineRichard Haseltine Posts: 102,252
    edited December 1969

    I think the inverse square is in the old DS3 manual, though I can't remember where that lives now (assuming it does still live).

  • SimonJMSimonJM Posts: 5,997
    edited December 1969

    Szark said:
    Thanks Simon yes indeed http://www.daz3d.com/forums/discussion/29667/ but crudely put it in real simple terms Increasing the intensity of a point light does cast a wider and brighter spread of light. I think this is when a lot of newcomers get put off with jargon and math get thrown at them without an simplified explantion what it means in real terms when dealing with certain lights in the CGI world. But what you say is true light just keeps on travelling. Do you mind if I use that Simon as it would make for a good intro to the inverse sq law, then if folks want to know more they can go and research this law when or if they feel like it on their own.

    Of course you can use it ... :) Not sure who developed the idea/theory in the first place though (I was bunking off school when they discovered it ... ;))

  • SzarkSzark Posts: 10,634
    edited December 1969

    Thanks Richard I waded through the DS3 manual the other day and there was no mention of this, well not that I could find. There is only two sections on Point Lights that I could see.

    Thank you Simon. LOL

  • Takeo.KenseiTakeo.Kensei Posts: 1,303
    edited December 1969

    Is that really important for a point light, when speaking in the perspective of an artist?

    I don't really see a way to check other than having the code but I never try to measure light intensity from the distance to the center of the point light

    And I rather use linear point light

    It's when you have to code one that you must think about these thing.

    OK one way would be to code one pointlight shader with what you'd want to have and compare to DZpointlight but sometimes you can also get the base idea and make some variations in the code

  • SzarkSzark Posts: 10,634
    edited December 1969

    In terms of education I think it is important to get the facts right, which is my only concern and the topic of the thread.

    But I am with you Takeo on a purely artistic point of view to me it isn't relevent at all. It does the job I want it to do, end off. But if I am going to share knowledge I need to learn more myself and I go looking for the answers, if that fails I ask here. But I would prefer finding the correct information myself with the limited skills I have. If I see information out there that contridicts each other I have to ask, way and where can I find to info to make sure it is correct. They are some folks that like to learn the more technical side of things and some don't care. I try to cater for them both at some level.

    Nice idea to check too Takeo I shall give that a try, no not the coding but a shader mixer point light comparison. ;)

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