Ue5 light shadow basic shadow full resolution sawtooth shadow solution lumen

Direct light shadow DirectionalLight shadow

Three Shadow ：1、 Ray tracing shadow;2、shadow maps;3、Virtual Shadow maps( Turn on DX12);

shadow maps：

1、Dynamic Shadow Distance Maps(CSM)： The closer you get , The higher the accuracy , The sharper the contrast ; conversely , The softer ;

2、DistanceFieid Shadow Distance( Distance field )： For medium and long distance scenes, you can use , It saves resources ;

3、Far Shadow Cascade Count（CSM）： You need to turn on the series in the direct light now , Then manually open the model that needs to be opened ; Or it won't work ; This can be turned on selectively ;

this 3 Can be used together ;

shadow Bias： To solve the offset of direct light shadow ;

shadow Filter Sharpen : The softness of shadows ;

The default role is CSM, The accuracy is relatively low , It can be opened separately inset shadow;
After opening shadow It will be hard or sharp , Can cooperate with the direct light Shadow Resolution Scale To soften the edges ;

For frequently adjusted parameters, you can right-click to add them to common or favorite , You will see it on the top of the detail panel for easy adjustment ;

Point source , Spotlights , Area light sources can be adjusted with this ;

Sometimes higher shadow quality is needed , It can be changed to virtual shadow -Virtual Shadow Maps


You can adjust the virtual and real shadow in the light detail panel ; Half shadow ？

To sum up 2 Try to avoid situations ： One is that the light coverage is particularly large , One is that the model is very small ; There will be situations where the light cannot be adaptive, resulting in poor shadow quality ;


There is also a case of light , When the model proportions are reasonable and appropriate , Jagged edges of shadows , At this time you can pass 2 There are three ways to solve ：

The first solution is ： Let the coverage area be slightly larger ;
The second solution is ：r.Shadow.Virtual.ResolutionlodBiaslocal -1/-2

Directional light , This situation cannot be solved , Itself is calculated by distance , So we need to consider replacing spotlights to simulate direct light ;

Another case is the close-up of the camera , This situation will also occur when it is particularly recent , Adaptive has reached its limit , At this time, it can be solved by improving the scope ;r.Shadow.Virtual.Clipmap.FirstLevel 6（ Default ） You can change to 3;





The above are normal or different mesh Shadow processing state of ;Mesh To Nanite mesh after ,
Nanite mesh Virtual shadows will be used uniformly by default ; Will overwrite CSM, Range field shadow ,

If you want not to change to Nanite mesh Virtual shadows are also enabled uniformly in the case of , You can use a command ：

r.Shadow.Vittual.UseFarShadowCulling 0;

because Nanite Mesh Temporarily not supported WPO, So we used WPO Of Nanite Mesh The optimization method is , A command ：

r.Shadow.Virtual.Cache.MaxMaterialPositionInvalidationRange 1000 （ Set the distance ）1000 Unexpected mesh Will be optimized ;

LowPoly Mesh A problem that will arise

Solution ：

1、 Command line ：r.Shadow.Virtual.NormalBias 5( The shadow offset value is a little more ); This will lead to the loss of detail shadows of models with a lot of details ：

2、 Increase the number of faces ：



summary ：

Ray tracing shadows ： It needs to be turned on first ,

If the model is converted to Nanite Mesh There will be problems later , There is a parameter that can be adjusted ：

The scene model is recommended to use Virtual shadow , Raytraced shadows still have some problems , Performance will also consume a lot ;

Indirect light and shadow

Lumen Dynamic global light , Indirect lighting ;

By changing this value, you can sample these little things ;