Contact shadows override reference

To edit properties in any Volume component override, enable the checkbox to the left of the property. This also tells HDRP to use the property value you specify for the Volume component rather than the default value. If you disable the checkbox, HDRP ignores the property you set and uses the Volume’s default value for that property instead.

Property	Description
State	When set to Enabled, HDRP processes Contact Shadows for this Volume.
Length	Use the slider to set the length of the rays, in meters, that HDRP uses for tracing. It also functions as the maximum distance at which the rays can captures details.
Distance Scale Factor	HDRP scales Contact Shadows up with distance. Use the slider to set the value that HDRP uses to dampen the scale to avoid biasing artifacts with distance.
Min Distance	The distance from the Camera, in meters, at which HDRP begins to fade in Contact Shadows.
Max Distance	The distance from the Camera, in meters, at which HDRP begins to fade Contact Shadows out to zero.
Fade In Distance	The distance, in meters, over which HDRP fades Contact Shadows in when past the Min Distance.
Fade Out Distance	The distance, in meters, over which HDRP fades Contact Shadows out when at the Max Distance.
Opacity	Use the slider to set the opacity of the Contact Shadows. Lower values result in softer, less prominent shadows.
Bias	Controls the bias applied to the screen space ray cast to get contact shadows. Higher values can reduce self shadowing, however too high values might lead to peter-panning that can be especially undesirable with contact shadows.
Thickness	Controls the thickness of the objects found along the ray, essentially thickening the contact shadows. It can be used to fill holes in the shadows, however might also lead to overly wide shadows.
Quality	Specifies the quality level to use for this effect. Each quality level applies different preset values. Unity also stops you from editing the properties that the preset overrides. If you want to set your own values for every property, select Custom.
Sample Count	Use the slider to set the number of samples HDRP uses for ray casting. Increasing this increases quality at the cost of performance.