Announcement

Collapse
No announcement yet.

4.19 Physical Lights

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Originally posted by rosegoldslugs View Post


    No I'm in the same boat as you. I don't see the point in even using the manual options. The cinematic camera/ new DoF are based on physical sensor and lens settings, but I haven't seen anything where they're tied together so really I have no idea what else they'd be used for other than people wanting to match a particular setup for a very specific reason.
    Right now, I can really only use the manual settings as a sanity check for my values. But currently there's no way to "eye adapt" between EV values in manual, so I'm forced then to use Histogram/Basic for getting that effect, but those values have no correlation to real life values. I get it - Unreal has to support legacy projects and such, but it's just not at all intuitive of what values should be. Like Daedalus51, I'd love to have the option of a "Min/Max Aperature/F-stop" adaptation in manual mode. This way I know for sure what a scene should be looking like, since I would have real life equivalent to compare to.
    Lighting Artist - Defiant Studios

    Comment


      Originally posted by k.mermelstein View Post

      Right now, I can really only use the manual settings as a sanity check for my values. But currently there's no way to "eye adapt" between EV values in manual, so I'm forced then to use Histogram/Basic for getting that effect, but those values have no correlation to real life values. I get it - Unreal has to support legacy projects and such, but it's just not at all intuitive of what values should be. Like Daedalus51, I'd love to have the option of a "Min/Max Aperature/F-stop" adaptation in manual mode. This way I know for sure what a scene should be looking like, since I would have real life equivalent to compare to.
      It's a bit of a process, but you could use the chart on the Wikipedia page I linked above and use the Min/Max EV(once you enable extended range in the project settings) and use EV values based on your desired manual settings at ISO 100. With the correct settings, there's a very tiny difference between Manual mode and a corresponding EV. I haven't tried the default min/max settings, but yeah I'm assuming since it's not with the extended luminance range, the values don't necessarily line up with the huge range required.
      Lighting Artist @ Rockstar Games
      ArtStation
      Twitter

      Comment


        Originally posted by rosegoldslugs View Post

        It's a bit of a process, but you could use the chart on the Wikipedia page I linked above and use the Min/Max EV(once you enable extended range in the project settings) and use EV values based on your desired manual settings at ISO 100. With the correct settings, there's a very tiny difference between Manual mode and a corresponding EV. I haven't tried the default min/max settings, but yeah I'm assuming since it's not with the extended luminance range, the values don't necessarily line up with the huge range required.
        Thanks - I have not turned on the extended range in project settings, I'll look into that.

        But I think the point too overall is that it's still a bit involved process, when this sort of thing should be a lot easier to work with. Those us hanging out in a photorealism space would appreciate a little more out of the box solution. I really like the idea of using manual because I have real life photographic data and images to compare to, and I'm a bit disappointed that this isn't a feature in Unreal when I've used this sort of system in nearly any other engine I've worked in.
        Lighting Artist - Defiant Studios

        Comment


          First of all thank you for clarifying my points rosegoldslugs!
          As k.mermelstein mentioned, things are waaaay to complicated at the moment, on top of that some of the values like lumen are not really working like they should. I hope the next versions of Ue4 will support physical lighting like it should be, you put your real life values into the editor and you get the right lighting result back.

          Comment


            Originally posted by Daedalus51 View Post

            Why is the camera exposure setting in line with sunny 16 but the one system I need to use to have a range of lets say f8 to f10 for gameplay is not? Thats my only issue with this Its for the sake of understanding it better and streamlining it for less experienced people. Also it would be easier touse the samevalues for cutscenes and gameplay (with the difference that gameplay would have a range of a few stops if you want)

            Cheers!
            I'm not sure if anyone answered exactly yet why this example doesn't work so I wanted to clarify. f/8 is not the same as EV100 8. Aperture is only one variable in the equation and EV100 is the total result.
            • The first image is using fixed exposure of EV100 8
            • The second image is using 1/125s, f/8, and ISO 100 it looks like.
            Maybe it'd be nice to work with variable shutter or f-stop (or ISO), but the result is always a brighter or darker image and EV100 gives us this in one simple number. Documentation would help

            Comment


              I just got 4.21 and am back at this.
              Can't get my head around it as usual.

              At 125000 lux and sunny 16 settings why is my desert so dark?
              Attached Files

              Comment


                Bump. whether I use manual settings or putting EV100 on 16, I'm getting same dark results. Really need some help with that.

                I'm not even sure if I'm doing it wrong or it just doesn't work properly, like before.

                Comment


                  1/125, ƒ16, and ISO 100 is closer to EV15. With a pure white card, fully rough facing up, I increased the sky brightness until the card read about 25,000 Lux. I increase the sun to about 135000 Lux, bringing the final card reading to 125,000 Lux. With these settings, the previous values work well(also pretty close to perfect exposure for 18% gray), but EV16 is pretty dark, but if we follow typical EV measurements, EV16 is mainly for bright subjects on snow or sand, which explains why it's much darker than we expect. EV15, for 1/125, ƒ16, at ISO100 should look correct provided the intensities are all accurate and your materials are in the proper range.

                  Try raising your sun angle to be more in line with a mid-day angle and increase the intensity. Also try measuring a white card with the Pixel Inspector. My sun at 135000 is only about 99,000 Lux, so that's probably why it looks so dark to you.

                  Attached Files
                  Lighting Artist @ Rockstar Games
                  ArtStation
                  Twitter

                  Comment


                    Originally posted by Maximum-Dev View Post
                    I just got 4.21 and am back at this.
                    Can't get my head around it as usual.

                    At 125000 lux and sunny 16 settings why is my desert so dark?
                    Are you using a custom skydome ? If so, you also need to crank up the brightness multiplayer of your HDRI.

                    Comment


                      Originally posted by rosegoldslugs View Post
                      1/125, ƒ16, and ISO 100 is closer to EV15. With a pure white card, fully rough facing up, I increased the sky brightness until the card read about 25,000 Lux. I increase the sun to about 135000 Lux, bringing the final card reading to 125,000 Lux. With these settings, the previous values work well(also pretty close to perfect exposure for 18% gray), but EV16 is pretty dark, but if we follow typical EV measurements, EV16 is mainly for bright subjects on snow or sand, which explains why it's much darker than we expect. EV15, for 1/125, ƒ16, at ISO100 should look correct provided the intensities are all accurate and your materials are in the proper range.

                      Try raising your sun angle to be more in line with a mid-day angle and increase the intensity. Also try measuring a white card with the Pixel Inspector. My sun at 135000 is only about 99,000 Lux, so that's probably why it looks so dark to you.

                      I have several questions but, how do you measure the surface illuminance? I don't see such option in pixel inspector nor HDR visualizer.

                      Originally posted by A-J-K View Post

                      Are you using a custom skydome ? If so, you also need to crank up the brightness multiplayer of your HDRI.
                      I do, I just had hidden it in that picture. Wondering about how to measure surface illuminance though.

                      Comment


                        Originally posted by Maximum-Dev View Post
                        I have several questions but, how do you measure the surface illuminance? I don't see such option in pixel inspector nor HDR visualizer.
                        William.sch documented a good method a few pages back, which is similar to what I do at work as well. Essentially, you can do it from a sphere(easy to sample from any direction) or use a plane oriented towards any particular direction you want to measure. The material on either mesh needs to be pure white(1.0, not PBR white) and fully rough. If you lay the plane flat, horizontally, you're recreating a horizontally placed light meter, which is usually the case since IRL you don't really want to burn out the meter by pointing it directly at the sun.

                        With the Pixel Inspector enabled, and you're in game mode(nothing will happen if you're not), you can sample an area on the mesh. For the sphere, it's most likely the direction of the dominant light source or the top pole. For the plane, it's anywhere on the top face. It's a good idea to disable bloom, fog, DFAO/SSAO, and any other post-effect that might interfere with the scene color. The HDR input in the Pixel Inspector measures everything in luminance or cd/m² or nits, which is why you want to use a pure white material since luminance is based on color. Taking that HDR value and multiplying it by pi will give you the Lux value.

                        Lux is easier to find for any given lighting condition. Luminance is a good measurement if you're really trying to nail a sky material or emissive surface. With most Lux measurements online, they will include the sky contribution too. I will usually measure the skylight by itself and then the sky and sun to get the ambient in range first before the sun, since the sun measurement on a Lux meter can vary drastically based on the angle of the sun and card.
                        Lighting Artist @ Rockstar Games
                        ArtStation
                        Twitter

                        Comment


                          Originally posted by rosegoldslugs View Post

                          William.sch documented a good method a few pages back, which is similar to what I do at work as well. Essentially, you can do it from a sphere(easy to sample from any direction) or use a plane oriented towards any particular direction you want to measure. The material on either mesh needs to be pure white(1.0, not PBR white) and fully rough. If you lay the plane flat, horizontally, you're recreating a horizontally placed light meter, which is usually the case since IRL you don't really want to burn out the meter by pointing it directly at the sun.

                          With the Pixel Inspector enabled, and you're in game mode(nothing will happen if you're not), you can sample an area on the mesh. For the sphere, it's most likely the direction of the dominant light source or the top pole. For the plane, it's anywhere on the top face. It's a good idea to disable bloom, fog, DFAO/SSAO, and any other post-effect that might interfere with the scene color. The HDR input in the Pixel Inspector measures everything in luminance or cd/m² or nits, which is why you want to use a pure white material since luminance is based on color. Taking that HDR value and multiplying it by pi will give you the Lux value.

                          Lux is easier to find for any given lighting condition. Luminance is a good measurement if you're really trying to nail a sky material or emissive surface. With most Lux measurements online, they will include the sky contribution too. I will usually measure the skylight by itself and then the sky and sun to get the ambient in range first before the sun, since the sun measurement on a Lux meter can vary drastically based on the angle of the sun and card.
                          Thanks for the explanation. I do still find it darker than expected though.

                          1. I've adjusted the sky dome brightness until skylight at 1 intensity gives me an HDR value of around 7960 which results in 25,000 Lux after multiplying by 3.14.
                          2. Then added directional light on top of that, with 100,000 Lux which results in HDR value of around 40,000 which results in around 125,000 Lux after multiplying by 3.14.

                          Here is what I get:

                          Click image for larger version  Name:	5112.jpg Views:	1 Size:	319.9 KB ID:	1556254

                          Here's what I expect to get:


                          Click image for larger version  Name:	whitecamelwithdecorativesaddlestandsinbrightdesertsuninBY1915.jpg Views:	1 Size:	225.2 KB ID:	1556253


                          There's a very large difference in both pictures and I still fail to see why. Also consider the fact that my light source is facing down, it goes darker with a 45 degree angle.
                          Last edited by Maximum-Dev; 11-26-2018, 07:23 PM.

                          Comment


                            I'm far from beeing an expert on lighting but for me it looks like your dark albedo eats up most of your light. Especially since you camera setup looks just right.

                            Comment


                              Originally posted by A-J-K View Post
                              I'm far from beeing an expert on lighting but for me it looks like your dark albedo eats up most of your light. Especially since you camera setup looks just right.
                              Ground texture isn't really that dark. It looks about right actually. View from buffer

                              Click image for larger version  Name:	512.jpg Views:	1 Size:	215.9 KB ID:	1556295


                              Edit: Also white plane in previous post isn't shining white either.
                              Last edited by Maximum-Dev; 11-26-2018, 08:27 PM.

                              Comment


                                Yeah but it is a lot darker than the ground on your reference... Even you don't want to use it for your actual scene i would try "for test purpose" a brighter sandy texture like on your reference to check how lighting acts or simply change the albedo color.

                                Comment

                                Working...
                                X