You can look at the height map you import. The terrain engine reads the brightness information of the height map and maps it to the Z value of the terrain. When building a terrain, some people think that the ground should be the black part near the height map, which prevents the terrain from digging down into the river. The height map has 0-255 color levels, and the terrain level should be at 127 so you have enough height map information for editing on the Z-axis.
You can correct your height map in World Machine using the Rescale node.
你可以观察下你导入的高度图，游戏引擎的地形是读取高度图的亮度信息来映射到地形的Z值。一般构建地形的时候有些人觉得地面部分应该是靠近高度图的黑色部分，这样会导致地形无法向下挖河流。高度图有0-255个色阶，地形水平面应该在127，这样你才有足够的高度图信息以供你在Z轴上的编辑操作。
你可以在World Machine 中，使用Rescale节点修正你的高度图。