View Factor (Fp→s Vs. Fs→p ) + MRT

Hi Mostapha and Chris,

I realized that somehow we are using similar methods to calculate View Factor. I just did a comparison to see how accurate is LB by considering the sky dome patches as a reference for rays ( as yo said and I’m wondering why!). The way that it distributes points on an unit sphere doesn’t seem efficient and it needs huge number of rays to be accurate which is more close to the Monte Carlo method and time consuming process while for a sphere in the middle of a cube using 2500 rays seems more than enough.

In addition, what is not clear for me is do you convert Fp→s to Fs→p to calculate MRT considering how surfaces see the object or a person?



I would imagine that its based on the Monte Carlo method since Radiance and inherently Daysim use this method. Haven’t gone that deep into the code though.


Hi Navid,

Chris is the right person to reply to this question but nevertheless can you help me to understand the question better.

  1. Which component/method in Ladybug are you using for this comparison?

  2. What does NV stand for?


Hi Mostapha,

I’m using “IndoorViewFactor”

Assume NV is a similar method