Join Brian Bradley for an in-depth discussion in this video Automated Exposure Control, part of V-Ray 3.0 for 3ds Max Essential Training.
- When we first add a new physical camera to a scene, one of the things that we are instantly going to want or need to be able to master is the way in which it controls exposure in the scene. Seeing as this works quite a bit differently than Max's standard exposure controls, such as the mental ray photographic option, or even V-Ray's legacy physical camera model, we're going to spend the next two videos looking at the options and controls available to us. Specifically in this video, we will look at how we go about working with the somewhat automated target exposure method.
Now, we already have in our start scene here, a newly set up 3ds Max physical camera. This was added using the ctrl+c keyboard shortcut method that we have already demonstrated. Perhaps one of the first things we may notice as we come over to the command panel and take a look in the Exposure rollout is that all of the controls are actually grade-out. Well, almost all - we do have this Install Exposure Control option available to us, which, although a little unfortunately worded in my opinion, is just Max's way of telling us that we don't currently have any kind of exposure control enabled, that the physical camera can work with.
Indeed, if I just hit the 8 key to bring up the Environment and Effects dialog, you can see that this is very true. We can fix this, though, by either enabling the Physical Camera Exposure Control from the drop-down that we have here, which as you can see, brings the camera exposure controls to life. Or we could, if I just set that back to no exposure control, click the install button in the command panel. Which, in the end, produces exactly the same result. Once enabled, then, the question we are interested in answering is how do we go about controlling exposure using the default options that we see here.
Well, looking at what we have available, you can hopefully see why we have already given ourselves a primer on just what EV are, exposure values are, and how they work given that EV controls are all we have to work with here. In the camera's Exposure rollout, we have an EV target control, and in the Environment and Effects dialog, we have an exposure parameter that can be applied to any non-physical cameras in the scene, and an EV compensation parameter that will essentially be added to the already existing exposure target values that have been set up on any physical cameras that we have in the scene.
It is probably also worth noting here that we are, by default, going to be working with Per camera exposures in our scenes. This means that every physical camera that we create can have a different exposure setting applied to it according to its placement in the scene and to the requirements of the shot that we want from it. We can, if we want, switch this behavior in the Environment and Effects dialog and work instead with a global exposure setting. Doing this will tell Max to ignore any exposure settings that have already been applied to our physical cameras, and instead apply this single exposure value to all of the physical cameras in the scene.
One of the cool things that we can do whilst using Per camera controls is mix both physical and standard cameras in the scene, with the defaults having been set up here to give us the same exposure results from both camera types. Well, to see how all of this works, let's get set up to take a render. Now, if you have been working through, or maybe simply watching through the exercises that we have already covered in the course up to this point, you will know that our start seed here has been set up to give us a mid to late afternoon looking render on a clear sunny day.
Taking a cue from our primer on exposure values exercise then, a good starting point for an EV target here would be a roundabout value of 15, with 15 being the typical EV of a clear, bright, sunny day. Seeing as we are looking at a mid to late afternoon scenario here, though, let's try setting a target EV of 30. Now, what you may have spotted as I hit the Enter key to lock that value into place there, was the fact that the grade-out ISO value setting just above actually changed.
This is because, rather than being a true EV system, which is already noted, can throw up a variety of shutter speed and aperture setting for a single exposure value, what we are actually working with here is an auto-ISO mode. Meaning, we can set our physical camera's aperture and shutter speed to whatever values we want and if we then need to make a change of exposure in the scene, Max will make the correction by updating the ISO value only, which makes perfect sense, seeing as ISO is the only part of the exposure triangle that doesn't control other effects on the physical camera.
If we take a render now, the result that we get shows that our system is working as expected with the target EV giving the expected feel to our render. Now, the idea of having to manually tweak a whole bunch of Per camera exposures in a scene probably sounds a little bit unappealing. If the client, the director, or indeed whoever is in charge of art direction, suddenly decides that all of the shots in the scene need to be a little bit brighter or a little bit darker, we may all of a sudden feel that this Per camera exposure isn't quite as helpful a workflow as we thought.
Which of course, is exactly why we have this EV compensation parameter in the Environment and Effects dialog. Dialing in positive values here will produce brighter renders from all of the physical cameras in the scene, whilst negative values will, of course, produce darker images, making this a very quick and easy way to effect exposure on all of the physical cameras in our scene in one easy step.
- Using the new UI elements, Quick Settings, and revamped Frame Buffer
- Understanding color mapping modes
- Adding V-Ray light types
- Working with the V-Ray Sun and Sky systems and dome light
- Using irradiance mapping and light cache
- Working with diffuse color maps
- Making reflective materials
- Creating a translucency effect
- Using the new SSS and skin shaders
- Ensuring quality with image sampling
- Working with the adaptive subdivision engine
- Controlling the physical camera
- Working with FX tools such as VRayFur and VRayMetaball
- Stereoscopic 3D rendering
- Using Render Mask
Skill Level Intermediate
Q: This course was updated on 02/02/2016. What changed?
A: We added tutorials on the new 3ds Max camera tool, which replaces the defunct V-Ray Physical Camera. The author also includes a method for creating a V-Ray camera via scripting.
Q: This course was updated on 04/19/2018. What changed?
A: New videos were added that cover V-Ray 3.1 to 3.3 updates.