3D models may have different axis designations and different handedness for positive and negative sides of the axis. These conventions vary by 3D model format, and in some cases are not standardized.
If the model appears in the wrong orientation, use the following tools to correct it.
Select the mesh with the Digitizer tool, and right-click to the Vertex Editing menu to see these options.
Reverse the vertex normals of selected meshes
The vertex normals describe how the light interacts with the mesh. Reversing them will change the shadowing effects on the mesh. Use CTRL+N to show vertex normals, or N to toggle through display modes for normals.
Example
In this example, the snowman on the left has had the normals reversed, so that the shading of the lower two snowballs is darker and shadowed, compared to the original model on the right, where the bottom two snowballs are highlighted. The second image shows the models with Vertex Normal display enabled. The blue vectors point into the model on the left (where the vertex normals have been flipped), and point out of the model on the right, which would be a more typical face orientation for a 3D object such as this.
Reverse the faces of selected meshes (clockwise to CCW or vice-versa)
The face normals define the orientation of the faces. Changing the order that the vertices of the face are interpreted (clockwise or counterclockwise) will change which side of the face is the front and which is the back. This changes the texture application, as well as backface culling when enabled. Use SHIFT+N to show face normals, or N to toggle through normal display modes. Use CTRL+B to toggle backface culling.
Example
In this example the model on the left has had the faces reversed. With a structure like this, the effect is the turn the model inside out, so the textures ar facing the inside rather than the outside. The shadowing of the windows appears on the inside instead of correctly on the outside like in the original model on the right. Also note the differences in the roof. The second image displays the models with face normals shown in red vectors. The third image displays these models also with backface culling enabled. The walls closest to the camera have disappeared in the model to the right, because the camera is looking at the backside of the face now that the face has been flipped.
Perform Y-up conversion on the selected meshes (y= -z, z=y)
A y-up conversion will flip the model forward 90 degrees about the model origin. This means in the front view orientation (CTRL+SHIFT+F) , the faces on the front of the model facing the camera will become the bottom of the model. If the model appears as if lying on its back, this will flip it upright.
Example
In this example, the tower on the left was loaded and appeared as if lying on its back from the front view (CTRL+SHIFT+F) . A Y-up conversion was performed to flip it upright, as in the model on the right side.
Perform Z-up conversion on the selected meshes (y=z, z= -y)
A z-up conversion will flip the model backward 90 degrees about the model origin. This means the faces pointing at the camera in the default view will become the top of the model. If a model appears as if lying on its face, this will flip it upright.
Example
In this example, the tower on the left was loaded and appears as if lying face down from the front view (CTRL+SHIFT+F). The top of the model is facing the camera. Performing a Z-up conversion flips the model upright, as in the model on the right side.
Change mesh handedness (y= -y, z=-z)
This will flip the model upside down about the model origin.
Example
In this example the pole on the left was loaded upside down. Changing the mesh handedness
See Also Rotating and Scaling Features for additional mesh orientation options.