Houdini 20.5 Nodes Geometry nodes

Sky Field from Map geometry node

Modifies a Sky Field using an image saved on your disk.

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Since 20.0

Overview

This node loads a grayscale texture image file as a Sky Field volume. This lets you use cloud photography as a Sky Field instead of generating procedural cloud noise. See How to create a sky for how to work with Sky Fields.

This node ignores the thickness of the clouds.

Parameters

Layers

Map Layer

The name of the volume to read the image map into.

The default value is sky.

Mask Layer

If a mask volume is wired into the node’s second input, this specifies which volume in the second input to use to mask this node’s effect, usually mask. Click the Add a Mask Paint button to paint the mask in the viewport, which automatically wires a Paint node into the second input.

The default value is skymask.

Blend

If a mask volume is wired into the node’s second input, this blends between the original input and the noise. When this is 0, this node does nothing and just passes through the original input. When this is 1, this node replaces the input with the noise.

The default value is 1.

Color Map

Operation

Specifies how to combine the image map with the incoming volume values.

Set

Overwrites the incoming volume. This is the default.

Add

Adds the image map to the existing volume.

Subtract

Subtracts the image map from the existing volume.

Multiply

Multiplies the image map by the existing volume.

Minimum

Outputs the minimum value of the existing volume and image map values.

Maximum

Outputs the maximum value of the existing volume and image map values.

Color Map

The image file used for lookup.

The default value is $HH/pic/Mandril.pic, which is an image of a mandrill.

Channel

The name of the channel to use (for example, diffuse_indirect or N). For ptex images, this specifies the index of the first channel (for example, 0 or 4). You can choose Luminance (the default), Red, Green, Blue, or Alpha using the button strip to the right of the text field.

Border Color

Border color when Decal wrapping is used. This becomes the adjustment value if the image is looked up outside the 0-1 UV range.

Source Color Space

The image’s colorspace.

Wrap

Determines how the image is evaluated when the texture coordinates are outside the range 0 to 1. The options are:

Repeat

(string value repeat). The image map repeats outside the range 0 to 1. Basically, the integer component of the texture coordinate is ignored.

Streak

(string value streak). Texture coordinates are clamped to the 0 to 1 range.

Decal

(string value decal). Coordinates outside the range 0 to 1 will evaluate to the border color rather than an image color.

Map Placement

Translate

The translation applied to the image map’s UV coordinates.

The default value is 0.5, 0.5, 0.5.

Rotate

The amount to rotate the image map’s UV coordinate plane.

The default value is 0.

Scale

The uniform scaling of the image map’s UV coordinates.

The default value is 1, 1, 1.

Pivot

The local pivot point for the image map transformations.

The default value is 0.5, 0.5, 0.5.

Color Correction

Multiply

Scales the volume value by this amount.

The default value is 1.

Bias

Increases or decreases the bias for the low values of the volume.

The default value is 0.5.

Gain

Increases or decreases the gain for the high values of the volume.

The default value is 0.5.

Gamma

Applies gamma correction to the map volume. Values less than 1 darken the colors and increase the range of values for originally bright areas. Values greater than 1 brighten the volume and stretch out the range of values for originally dark areas.

The default value is 2.2.

Contrast

Expands or shrinks the overall range of tonal values. Values less than 1 push each color value towards medium gray (RGB values at 0.5). Values greater than 1 push each color value away from medium gray.

The default value is 0.

Complement

Complements or inverts the colors (subtracts each RGB component from 1). Complementary colors are opposite each other on the color wheel.

See also

Geometry nodes