Mipmapping in wpf

Try the following approach using VisualBrush - it produces clear, aliased texturing:

        <DiffuseMaterial x:Key="Material">            <DiffuseMaterial.Brush>                <VisualBrush RenderOptions.CachingHint="Cache">                    <VisualBrush.Visual>                        <Image Source="char.png" RenderOptions.BitmapScalingMode="NearestNeighbor" />                    </VisualBrush.Visual>                </VisualBrush>            </DiffuseMaterial.Brush>        </DiffuseMaterial>    </Grid.Resources>    <Viewport3D Name="myViewport">        <Viewport3D.Camera>            <PerspectiveCamera Position="0 0.5 1.5" LookDirection="0 0 -1"                           UpDirection="0 1 0" FieldOfView="120" />        </Viewport3D.Camera>        <Viewport3D.Children>            <ModelVisual3D>                <ModelVisual3D.Content>                    <GeometryModel3D Material="{StaticResource Material}">                        <GeometryModel3D.Geometry>                            <MeshGeometry3D                         Positions="0 0 0, 0 1 0, 1 0 0, 1 1 0"                         TriangleIndices="0 2 3, 0 3 1"                         TextureCoordinates="0 1, 0 0, 1 1, 1 0" />                        </GeometryModel3D.Geometry>                    </GeometryModel3D>                </ModelVisual3D.Content>            </ModelVisual3D>            <ModelVisual3D>                <ModelVisual3D.Content>                    <AmbientLight Color="#ffffff"/>                </ModelVisual3D.Content>            </ModelVisual3D>        </Viewport3D.Children>    </Viewport3D></Grid>