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We’ve been hard at work on the Progressive Lightmapper since we first showed it at GDC in March. Please watch the video below for a quick introduction to what the Progressive Lightmapper has to offer so far:


The Progressive Lightmapper is an unbiased Monte Carlo path tracer – it can bake out lightmaps with global illumination (GI) inside the Unity Editor. For the last 40 years, the point at which realtime raytracing will become possible in a realtime application has been 5 years in the future and it still is. So for now the Progressive Lightmapper will exist as an alternative backend for baked lighting only.

What about Enlighten? Enlighten is here to stay. Enlighten provides realtime GI and this cannot currently be achieved with a path tracer.


The aim of the Progressive Lightmapper is to make the workflow for baking lighting for a scene much better. In the current Unity release changes to the scene require a new bake and the results can only be shown when the bake is done. What Enlighten brought to the table is the ability to change lights in realtime and see the results immediately. However, changes to parameters, materials or geometry still require a rebake during which you get no feedback.

When iterating on – for example – baked shadows or the level of bounced lighting, waiting minutes or even longer between being able to make informed changes can be very frustrating. This effectively limits the quality you can achieve with your baked lighting. With the Progressive Lightmapper you will get almost immediate feedback. A noisy result at first, but rapidly improving directly in the Scene View.


It has the added benefit of being able to prioritize the parts shown in the viewport – once they have finished it will continue baking the rest of the scene outside of the viewport.

In addition, the Progressive Lightmapper is in many cases more robust. It bakes out indirect lighting at full lightmap resolution so it is less prone to producing artifacts there. The setup is simple; provide a UV unwrap or let Unity create one and set the baking resolution. All your knowledge of traditional baking tools apply. Also, we can more easily predict when it will be done, so a reliable ETA on when the bake will finish is shown on the progress bar.

ETA prediction

Finally, when you think the result is good enough you can stop the bake and the lightmaps are created for you from the current state. So if you want to increase samples and allow Unity to add quality to the bake during some downtime, you can crank it up, and stop as soon as you’re ready to continue working.

What does it not do?

It is not a replacement for realtime GI. It only works for baking in the Unity Editor, so you cannot bake from within your game. This rules out baking GI for procedural scenes in-game, or the ability to change the lighting setup for time of day and baking on load. We want to nail the baking workflow in the Editor before we take it further.

Also, it is not necessarily faster than baking with Enlighten. If you setup your scene well for Enlighten it can be very fast, so we cannot guarantee that all scenes bake faster with the Progressive Lightmapper. However, the time between starting a bake and getting some visual feedback will be significantly faster with the Progressive Lightmapper.

Finally, it does not yet support any specific hardware such as a PowerVR Ray Tracing enabled GPU or a regular GPU. Right now it runs only using the CPU cores for baking. Again, for the initial release we will focus on the workflow.

When can I have it?

When it is ready. :) We are currently in a closed alpha phase testing out the feature with selected game developers. Once we are happy with it we will provide an open beta.

Until we’re ready to ship an open beta, we’d love to hear your feedback on what we’ve shown thus far. Sound off in the comments below!


This is a collaboration between Unity and Imagination Technologies, and we would like to thank the following people:

  • Jens Fursund
  • Luke Peterson


56 replies on “In Development – Progressive Lightmapper”

Wow, this will be a game changer. Please release a BETA version! I’ve been waiting for this for over a year!

Hello Unity, This is a long question but please read and answer me.

I am making a huge map which includes 610 terrains and tons of buildings, what i do is that I use World Streamer asset to stream these objects from HDD when needed and when it is not needed, it destroys the objects and the terrains so everything is fine But the question is about the light mapping process. As it turns out, World Streamer requires a secondary scene (which is named “Working Scene”) with all the objects and all the terrains be there, So that it makes the main scene from the secondary scene. So all the objects and all the terrains should be present in the work scene, which means it is impossible to bake light maps for each of the objects in the scene using Enlighten, My question is, Can this new lightmap baking technique bake lightmaps of that huge scene or not? if no, what do you recommend me to do for it.

what will happen if i hit play during progressive baking?
will it pause until i exit play mode then continue baking? or will start all over from start?

Hello. Will this new lightmapper be able to bake directional lightmaps that interact with normal maps? Like Enlighten can, and Beast used to.

Want to see:

1. There should be NO BLACK SPACE on a lightmap. Use nearest neighbour colors and pad around the edges of islands, and fill black space in a similar way (as Beast did), so even low-res lightmaps will look good.
2. Alternative to “scale on lightmap”. Let us just specify a resolution per object, so we can force a single object to use a 512 map. Atlas them all later.

Also, this padding should be added to Enlighten too. I know you don’t make games, but it near impossible to use Enlighten for a serious game because of this.

It looks cool! Is progress lightmapper totally new lightmap engine for baked lightmap? I’m seriously struggling with enlighten lightmap engine during developing mobile game. enlighten really sucks for baked lightmap work. It has too many problem like slow baking time and dilation problem that cause texture leak with uv seam.

This looks cool. Thanks for your effort to improve this workflow.

You mention that Enlighten can be fast if set up properly. Can you point to any documentation or blog posts that describe how to properly set up an Enlighten bake, either for realtime or baked GI. Thanks.

Hi Ben we’re actually working on this exact tutorial, shows how to get an environment setup properly, taking it’s bake time from around 7 hours to around 2 minutes. Looking forward to sharing this soon, we’re working on it now, and will get it live as soon as we can.

This looks really useful!

I hope the Auto bake option is not going to cause stuttering in the editor, like it’s doing with the current light-mapper. “micro-stutters” that cause the editor to freeze for a moment, due to auto-bake, makes working in the scene during this time really unsatisfying.

Thanks for all the recent update videos/posts as well, I really appreciate that.

Looking forward to this feature as I’m sure I’ll get plenty of use out of it.
I have a few questions of my own…
-Will we, one day, be able to bake to vertices? This is both useful for low-end hardware, for obvious reasons, but for high end hardware too, where vertex counts sometimes rival texel counts.
-Since you are, basically, writing this lightmapper yourselves, any way you could include better solutions for dealing with seams? Like, say, inter-UV island blurring or proper colour extending beyond UV borders?

Hey Louis-Nicolas,

“Be able to bake to vertices” – it is on our radar, but it comes with it’s own set of problems and limitations, so just adding it is not an easy call. We are in a position to easily prototype it now though, but no promises. :)

“Inter-UV island blurring” – on the roadmap. It will happen when we’re closer to feature parity with Enlighten-based baking.

“Proper colour extending beyond UV borders” – actually, this just requires a small tweak in how we composite lightmaps. Filling the background is done during the lightmap import stage and the background texels just need to be marked as such in the source EXR file. I’ll poke back when this is in the build. :)

Looks pretty rad! Three questions:

1. Can I bake only ambient and leave direct light to a dynamic directional light.
2. Will it work with multi scene?
3. Will I be able to multiply the lightmap against a color in the shader?

Hey Daniel,

“1. Can I bake only ambient and leave direct light to a dynamic directional light.” – yes, but this is not specific to the new lightmapper, but rather to the mixed mode lighting rewrite. Please see: and
This will be supported in the progressive lightmapper soon.

“2. Will it work with multi scene?” – yes. No changes here compared to how it works with Enlighten. But a few fixes in that area are coming in separately.

“3. Will I be able to multiply the lightmap against a color in the shader?” – not related to the progressive lightmapper really. You can do that by e.g. modifying the Standard shader.

Seems great, no doubt!

One question – will there be a possibility to select to which UV channel to bake?
It would be useful even for the case that one wants to make baked textures inside the “source” 3D modeling software, which usually provides better control&flexibility of the result than Unity built-in system…

And in general – would the Standard Shader finally allow to set the UV channel, tiling and offset *individually* per each texture (it means per occlusion map, normal, emission…) as it is common in 3D modeling sw (and was often in pre-Unity 5 shaders…)?

But anyway, thanks for your invention and continuous effort!

Hey Ivan,
“Will there be a possibility to select to which UV channel to bake?” – currently there is a clash with the detail maps in the Standard shader, so we will allow for some control to resolve that.

Great start, But some of us badly need GPU or network rendering, I have a lightmap I have no generated yet due to the fact after 17 hrs it was not even half done. :( Keep up the great work!

Yes, Mortensen! a Network sharing GPU and CPU can help us to bake faster when we need power. in this way I can share CPU cores when I’m not using it. As for example a slider with how many CPU to share, a button on off to connect to the sharing network and other slider for how many CPU are use in my pc for making the rendering. SETI is an example. A counter of how much power we share. In this way the counter can go down when we need to bake.

Also thinking better, when is summer, since there is 35° at night and 45° long bad hot day and I do not want to use my CPU for 20 hs in my room. So asking the other hemisphere that in that case it will be in winter can help all us in preserving CPU and temperature distribution. In winter I need to hot my room, I can turn off the electric stove and use a little bit of CPU sharing power to maintain room temperature. Is not less expensive but reduce impacts.

Just this week we were discussing in the office about baking and the uncertainty of how long it would take, we’re working on some intricate scenes and we’re never quite sure how far along the bake is till its done. This will be an awesome tool for dev iterations, and getting a feel when addressing certain aspects of the scene we’re working on.
Looking forward to seeing it.

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