# DirtyHeightmapRegion(RectInt, TerrainHeightmapSyncControl)

> Marks the specified part of the heightmap as dirty.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.6/script-reference/unityengine.md)
* **Assembly:** UnityEngine.TerrainModule

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

### Parameters

**** (\[RectInt]\(/engine/6000.6/script-reference/unityengine/rectint)): The rectangular region to mark as dirty.**** (\[TerrainHeightmapSyncControl]\(/engine/6000.6/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/6000.6/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/6000.6/script-reference/unityengine/terraindata/syncheightmap.md).

If the current active [RenderTexture](/engine/6000.6/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/6000.6/script-reference/unityengine/terraindata/copyactiverendertexturetoheightmap.md) instead.

This function sends out the OnTerrainChanged message with [TerrainChangedFlags.Heightmap](/engine/6000.6/script-reference/unityengine/terrainchangedflags/heightmap.md) if you pass [TerrainHeightmapSyncControl.HeightAndLod](/engine/6000.6/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/6000.6/script-reference/unityengine/terrainchangedflags/delayedheightmapupdate.md).