Daylon Leveller is a terrain/heightfield modeling program made by Daylon Graphics Ltd. of British Columbia, Canada. Leveller documents appear in a two-paned window showing a nadir (top-down) view of the heightfield and an OpenGL-based view showing the heightfield (and related elements) in 3D. Sculpting and most of the other tools can be used on either pane. Edits are reflected immediately in both views, providing an interactive feel to the modeling process. Modeling is based on a paint-program metaphor similar to Adobe Photoshop, with brushes, selection tools, etc. Textures and water level can be applied also. Heightfields can be planar (flat) or distorted using UV displacement mapping onto spheres, sphere sections, cones, cylinders, etc. Vector shapes are supported using a separate vector layer, and can be used to situate edits and generate heightfield selection masks and formations. For civil engineers, cut/fill and cross-section analysis is available too.