United Kingdom
Joined: Sep 23, 2026
Post Count: 5
Status:
Offline
Planning LED Lighting in a Room Designed with Sweet Home 3D
Hi everyone,
I’m interested in how people plan lighting when designing a room in Sweet Home 3D.
When arranging a kitchen or living room, how do you represent LED strip lighting under cabinets, along shelves or around ceiling details? Do you use standard light sources to approximate the effect, or is there a better way to create a realistic preview of indirect lighting and shadows?
I’d also be interested in any tips for choosing light positions and colour temperatures to make the final render look more natural.
Netherlands
Joined: Apr 8, 2022
Post Count: 1833
Status:
Offline
Re: Planning LED Lighting in a Room Designed with Sweet Home 3D
First of all you have to know that there are two types of lighting in a scene: The lights that you see and the effects of (other) light sources that cause the lighted result.
For the lights that you see you can use any light from the catalog or create your own light. Don't expect those to actually light the room or other furniture. That rarely works well. You give them a low light power so you see the light as if it is on.
Then you light the room itself. That is the most difficult and I will leave explaining this to our respected member GaudiGalopin who is an absolute expert in lighting rooms with invisible hemispheres and/or using AI to create a perfect photo.
You can see several examples on my webpage with streetlights . The glass of the lights have a low power setting just to show it as a light but the actual spread of light is an invisible hemispere.
---------------------------------------- Dodecagon.nl 1300+ 3D models, manuals, and projects
Russia
Joined: Aug 13, 2022
Post Count: 746
Status:
Offline
Re: Planning LED Lighting in a Room Designed with Sweet Home 3D
Thank you for the high rating, Keet! Unfortunately, my experience creating real lighting in a room using SH3D has run into a problematic issue. Render time. Real lighting is always the sum of direct and reflected light from surfaces. SH3D does not allow modeling reflected light (reflections). And it is precisely these that create a realistic image. Therefore, in SH, you get black, unlit areas that do not exist in reality. Light penetrates everywhere, but not in the SH renderer. You have to simulate such reflections using numerous additional light sources. And this makes the render unrealistically slow. There are simplified solutions that allow you to simulate reflections from the floor. These are invisible light panels directed from the floor towards the ceiling (1-2% 1cm above the floor) and a panel on the ceiling (just 1cm below the ceiling level) with a 2-5% direction towards the floor. This is the fastest rendering of all possible solutions with simulated reflexes. But complete realism cannot be achieved in this way. Maximum realism is achieved by a multitude of hemispheres, but this method makes the rendering look like an eternity.. The more realistic and difficult the attempt to simulate reflexes, the longer the rendering. My experiments took 20–30–40 hours for a single render, which is awful. But I don’t see anything else in the program. Unfortunately, artificial intelligence imitates reality much more accurately. Therefore, we can be glad about the program’s signature style, where reality isn’t the main goal. The main thing in SH3D is the ease of creating space; realism isn’t the priority.
United Kingdom
Joined: Sep 23, 2026
Post Count: 5
Status:
Offline
Re: Planning LED Lighting in a Room Designed with Sweet Home 3D
Thanks, that distinction helps. I hadn't considered treating the visible fitting separately from the actual light it casts. For under-cabinet LED strips, would you normally use several invisible light sources to create the spread across the worktop, rather than relying on the strip model itself?
United Kingdom
Joined: Sep 23, 2026
Post Count: 5
Status:
Offline
Re: Planning LED Lighting in a Room Designed with Sweet Home 3D
That’s a really useful explanation of the trade-off between realistic lighting and render time. Spending hours on a single render seems impractical for most room designs, so a simpler approximation makes sense. For something like under-cabinet LED strips, would you use the floor and ceiling panels approach as a starting point, or is it better to add local light sources just where the strip illuminates the worktop?
Netherlands
Joined: Apr 8, 2022
Post Count: 1833
Status:
Offline
Re: Planning LED Lighting in a Room Designed with Sweet Home 3D
For something like under-cabinet LED strips, would you use the floor and ceiling panels approach as a starting point, or is it better to add local light sources just where the strip illuminates the worktop?
For only the led light on the counter top you can use a single invisible hemisphere that you resize so the bottom of the sphere contours where the light touches the counter. That is what I did with the streetlights. The high streetlight has a single invisible hemisphere that is resized to outline where the light goes. It's a little elevated to avoid a sharp edge where the light touches the floor. It it's a long led-light you can one or two extra hemispheres.
For the general lighting of the room you can use the light panels. It depends if you want to render or use AI to generate a photo. You can test-render by not using the highest setting, that should go a little faster. You can also try multiple panels instead of hemispheres. A panel is a single face that produces light, a hemisphere has many faces and each one acts like a light panel, thus it takes much more processor time to render.
Alternatively you can use this little library I quickly created with two half-tube light sources. One visible, one invisible. You can stretch, resize, and elevate how you want. These only have 6 faces, much, much less than a hemisphere. You can place the invisible one halfway between the counter top and bottom of the LED strip. That is what you se in the image, the invisible light is at elevation 120cm. (The light is resized to 50cm wide, 4cm deep and 1cm high, light power 8%).
---------------------------------------- Dodecagon.nl 1300+ 3D models, manuals, and projects
Unfortunately, my experience creating real lighting in a room using SH3D has run into a problematic issue. Render time. Real lighting is always the sum of direct and reflected light from surfaces. SH3D does not allow modeling reflected light (reflections). And it is precisely these that create a realistic image. Therefore, in SH, you get black, unlit areas that do not exist in reality. Light penetrates everywhere, but not in the SH renderer. You have to simulate such reflections using numerous additional light sources. And this makes the render unrealistically slow. There are simplified solutions that allow you to simulate reflections from the floor. These are invisible light panels directed from the floor towards the ceiling (1-2% 1cm above the floor) and a panel on the ceiling (just 1cm below the ceiling level) with a 2-5% direction towards the floor. This is the fastest rendering of all possible solutions with simulated reflexes. But complete realism cannot be achieved in this way. Maximum realism is achieved by a multitude of hemispheres, but this method makes the rendering look like an eternity.. The more realistic and difficult the attempt to simulate reflexes, the longer the rendering. My experiments took 20–30–40 hours for a single render, which is awful. But I don’t see anything else in the program. Unfortunately, artificial intelligence imitates reality much more accurately. Therefore, we can be glad about the program’s signature style, where reality isn’t the main goal. The main thing in SH3D is the ease of creating space; realism isn’t the priority. 
