This page provides information about the V-Ray Exposure Value, V-Ray Film Sensitivity and V-Ray F-Number nodes in Grasshopper.
Overview
The Exposure Value node calculates exposure based on ISO, F-Number and Shutter Speed inputs. The F-Number node calculates a F-number value for a given Defocus value. The Film Sensitivity node calculates an ISO value based on EV, F-Number and Shutter Speed inputs.
These three components work together with the V-Ray Camera component.
V-Ray Exposure Value
Input Parameters
ISO (Number) – The film speed (ISO) parameter determines the sensitivity of the film and consequently the brightness of the image. If the ISO value is high, film is more sensitive to the light, the image is brighter. Lower ISO values result in a less sensitive film that produces darker images.
F (Number) – The aperture (f-number) parameter determines the lens speed and consequently the brightness of the image. Additionally, the f-number affects the Depth of Field of the camera. The smaller the f-number is, the more narrow the depth of field is.
SS (Number) – Determines the exposure time for the virtual camera. The longer this time is (small shutter speed value), the brighter the image is. Vice versa, if the exposure time is shorter (high Shutter speed value), the image gets darker.
Output Parameters
EV (Number) – Specifies the exposure value based on the ISO, shutter speed and the F-number.
V-Ray Film Sensitivity
Input Parameters
EV (Number) – Determines the exposure value.
F (Number) – The aperture (f-number) parameter determines the lens speed and consequently the brightness of the image. Additionally, the f-number affects the Depth of Field of the camera. The smaller the f-number is, the more narrow the depth of field is.
SS (Number) – Determines the exposure time for the virtual camera. The longer this time is (small shutter speed value), the brighter the image gets. Vice versa, when the exposure time is shorter (high Shutter speed value) the image gets darker.
Output Parameters
ISO (Number) – The film speed (ISO) parameter determines the sensitivity of the film and consequently the brightness of the image. If the ISO value is high (film is more sensitive to the light), the image is brighter. Lower ISO values result in a less sensitive film that produces darker images.
F-Number
Input parameters
D (Number) – Determines how sharp or de-focused the image looks outside a plane determined by the focus point. Also known as Focus Range.
Output parameters
F (Number) – The aperture (f-number) parameter determines the lens speed and consequently the brightness of the image. Additionally, the f-number affects the Depth of Field of the camera. The smaller the f-number is, the more narrow the depth of field gets.
Examples
Exposure Value component calculates EV based on the base camera parameters:
ISO component calculates the ISO based on the other base camera parameters and EV. The ISO component represents an easier way to adjust the camera ISO in order to match a given EV value:
The F-number component determines the calculations of the ISO and F-Number based on the defocus amount and the rest of the base camera parameters.
The F-number from Defocus is the easiest way to set up the desired Depth of Field without the need of additional calculations: