For example: if I use a section plane to show the interior of a house (and if I have shadows enabled), the sun will stream into that space as if the exterior wall doesn’t exist. This impacts daylight studies. And I suspect the current behavior isn’t often useful.
I suggest having an option in the section plane, or the object casting the shadow, or perhaps a global toggle. Maybe even just change the default behavior.
I’m aware of a workaround involving transparent PNG textures. I haven’t tried it, but it seems like a hassle.
A transparent plane over 70% will block the light but still allow visibility, I assume the workaround you mention. (second image on right)
Another option is available with Thea Render, which will respect the normal lighting in a scene despite a section plane in place. ( 1st image )
Yeah, I’ve been working on some sections with Thea render and it’s pretty cool, you get lighting, reflections and all as if the rest of the room is still there.
I remembered that you could also play with the effect you get by painting one side of a face with an opaque and the other with a transparent material, but unfortunately it doesn’t work. Shadow casting is determined by the material that the sun rays encounter first, so what you see depends on the side you are looking at and how the material has been applied. From inside the space you either see paradoxically an opaque face that light passes through, or a transparent face that casts a shadow.
Thanks for the helpful responses. The first method (2nd picture) doesn’t really work with a double-faced wall – at 70% opacity it’s barely see-through. I did have success using a PNG texture extracted from the model linked in my original post – fully invisible wall which casts shadows.
Actually, though I thought I remembered being able to do that in TWL, it seems I got it wrong. (I just did a test with a model I’m working on and it renders section shadows just as SU itself does.)
Time to make a feature request over at the Twilight forum, I guess!
Yes, a toggle button to cast shadows from cut part of the model would be very useful addition to Sketchup. Not only for shadow study but also creating beautiful section drawings that casts shadow elegantly and correctly on the wall surfaces.
In my opinion Sketchup’s greatest strength is ease of creating quick but beautiful construction drawings. Never saw a software that does it as good and as quick as Sketchup (and Layout).
This toggle button would take it to another level. I’m thinking of drawings similar to ones in the book ‘‘Manual of Section’’
I was looking for a solution for this, and I was able to come up with a solution, and it is placing the camera in the interior of the space:
Create a section plane (to be able to access the interior)
Use the [Position Camera] tool (using two points, one at 4’ height and one on the ground both located on the same vertical line)
Turn off the [Display Section Cuts] option…
Voila!
After this, you can zoom in/out and pan, but not orbit… as soon as you orbit the camera position will get reset.
Interesting! So does it let you zoom out beyond the height of the ceiling, even after turning off section cut? I’m assuming there is a ceiling in this model? Sounds like a useful exploit, if I understand it correctly.
I am sure you will be able to do this with the camera pointing horizontally, just need to pick to points perpendicular to the face you are tryin to look at… I was looking for a solution that allowed me to show shadows on a floor plan…
Thank you for sharing this! This is helpful for solar studies for interiors or if you have a large overhang and want to study lighting for landscape. How did you get your view into a perfect plan angle? I have to manually set the camera at a tilted angle in order to get the Position Camera tool.
Also, I’ve confirmed that the shadows will continue to ignore the section plane if you Save a Scene, Turn Layers On & Off, & Change the Date/Time.
(I just did a test with a model I’m working on and it renders section shadows just as SU itself does.)
