Massive getBounds() for GeoMipTerrain

I’m trying to make a character walk along GeoMipTerrain using a PhysicsCollisionHandler. Collisions are being registered, but the character moves along far above the visible landscape, as if the contours of the terrain were translated hundreds of units up. When I call terrain.getBounds(), as in the code below, it returns a normal center but a whopping radius. (The heightfield file is 257x257 px).

getBounds()

 bsphere, c (128 128 32.5997), r 10861.2 (

Code that generates GeoMipTerrain


        #zScale = sys.argv[zScaleIndex]
        zScale = 60
	heightfieldFile = sys.argv[heightfieldIndex]

	terrain = GeoMipTerrain("test")
	terrain.setHeightfield(heightfieldFile)
	terrain.generate()

        root = terrain.getRoot()

	root.setSz(zScale) 

	print root.getBounds()

If necessary, I have also uploaded the heightfield file. However, the same issue occurs with other heightfields.

Thanks for any information. New to Panda3D.