# DirtyHeightmapRegion(RectInt, TerrainHeightmapSyncControl)

> Marks the specified part of the heightmap as dirty.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.TerrainModule

```csharp
public void DirtyHeightmapRegion(RectInt region, TerrainHeightmapSyncControl syncControl)
```

### Parameters

**** (\[RectInt]\(/engine/6000.0/script-reference/unityengine/rectint)): The rectangular region to mark as dirty.**** (\[TerrainHeightmapSyncControl]\(/engine/6000.0/script-reference/unityengine/terrainheightmapsynccontrol)): Controls how CPU synchronization is performed.

### Remarks

Use this function only after you manually change the GPU part of the heightmap texture by rendering into it, or by using [Graphics.CopyTexture](/engine/6000.0/script-reference/unityengine/graphics/copytexture.md). Use the syncControl parameter to control how you want Unity to perform CPU synchronization. Unity queues the reading back of unsynchronized data (height data, LOD data, or both) until the next call to [TerrainData.SyncHeightmap](/engine/6000.0/script-reference/unityengine/terraindata/syncheightmap.md).

If the current active [RenderTexture](/engine/6000.0/script-reference/unityengine/rendertexture.md) contains your changes, and you want to copy a part of it into the heightmap texture, use [TerrainData.CopyActiveRenderTextureToHeightmap](/engine/6000.0/script-reference/unityengine/terraindata/copyactiverendertexturetoheightmap.md) instead.

This function sends out the OnTerrainChanged message with [TerrainChangedFlags.Heightmap](/engine/6000.0/script-reference/unityengine/terrainchangedflags/heightmap.md) if you pass [TerrainHeightmapSyncControl.HeightAndLod](/engine/6000.0/script-reference/unityengine/terrainheightmapsynccontrol/heightandlod.md) to the syncControl parameter. If you pass Height to the syncControl parameter, it sends out the OnTerrainChanged message with [TerrainChangedFlags.DelayedHeightmapUpdate](/engine/6000.0/script-reference/unityengine/terrainchangedflags/delayedheightmapupdate.md).