Heat map effect

(jerchristensen) #1

Hi everyone! So I’ve got an interesting project at work that I’m struggling with. I’ve been trying to create a heat map like effect that would show how a traffic radar might see a vehicle. I came up with the idea to use multiple fresnel effects layered over each other in different colors to show the strength of the reflected radar signals. This seems to work well for the engineers that I’m developing this for but only if you think of the camera as being the radar. What they would like is to be able to rotate the camera to a different perspective but still keep the red hot spot pointed at the radar source. I’m fairly new to Blender so there may be a real easy workaround for this, but I’m stymied. Any ideas?

Here’s an example of the effect I’m going for. So they would like to place our sensor where the camera currently is and then move the camera to where it could see the car and the sensor at the same time and the red parts on the car sill still be focused towards the sensor, not the camera.


(moony) #2

I guess what you need is to be able to do is map the colour of a face via a colour ramp to the angle of it’s normal relative to another object (like an empty).

I was watching a video a few days back where one objects material was affected by the position of another object - but I can’t for the life of me find it now.

(RickyBlender) #3

problem is that Fresnel is function of angles !

but you could try with camera mapping then would not change function of cam loc
and may be add a constraint with an empty to fix camera in right rotation / location

but hard to test can you load small sample file

happy bl

(Secrop) #4



(moony) #5

I didn’t want to name drop you again Secrop - but I suspected you might be along with a solution :wink:

OP - just to be clear how Secrop’s method works.

As well as the car - you need to add an empty axes object to your scene (this will represent the radar gun) and select it in the object drop down of the texture coordinate node.

Now your heat map will point in the direction of the empty axes (radar gun) - not the camera - and you can therefore position the radar gun anywhere you like in relation to the camera and car.

Color based on an angle between camera and object's origin?
(Secrop) #6

@jerchristensen, If you have an object for your radar (which you probably have for the visualization), then you don’t need the empty, and you can use that object directly in the ‘Texture Coordinate :: Object’ link.