OBJ Import
The OBJ Import and Export functions both have presets specific to other applications (i.e., presets in this menu), that make exporting to these programs a smooth as possible.
Simply select the program/preset to which you want to export from the drop-down menu.
Selecting Default will reset all values to their default states. Custom will be displayed if a default value for a given Preset is modified.
Save Preset...
Delete Preset...
Settings defined here can be saved as a preset in the Content Browser. First, click on Save Preset. A dialog window will open in which you can enter information regarding the preset. After clicking on OK, the preset will be displayed in the Preset menu. The currently selected preset (default presets cannot be deleted) can be removed from the list and the Content Browser by clicking on Delete Preset.
This factor can be found at numerous locations throughout Cinema 4D when importing or exporting foreign formats. Therefore, don’t be surprised if the term ,export’ is used if this factor is seen in an import function (this factor is explained as a whole here).
This factor lets you scale files upon import/export, i.e., practically all relevant numerical values saved in the file or those to be saved will be multiplied by this factor and then saved - or interpreted when loaded.
The unit at the right in turn defines how upon
- Import the numerical value saved in the file is converted to the current Cinema 4D unit. Example: if an X value of 1 is saved in the file and you define Feet, the X value will be converted to 30.48 cm in Cinema 4D (if centimeters are defined by default in Cinema 4D).
- Export numerical values are saved in the file. Example: an X value is set to 100 cm in Cinema 4D. If you define Feet for export, the exported file will save a numerical value of 3.281 (1 meter = 3.281 feet).
More information about units and scaling can be found in the Project Scale section.
Use this setting to define if vertex Normals should be imported/exported. Phong tags can be generated for import.
No information pertaining to Normals will be processed (and no Phong tag will be created upon import).
Selecting this option will cause a Phong tag to be generated. The Phong Angle can be adjusted using the setting of the same name below.
An OBJ file’s Vertex Normals information will be imported into Cinema 4D using a Vertex Normals tag. If Vertex Normals information is present, regular Phong shading via a Phong tag will be used.
If Normals is set to Phong tag, the Phong tags that are created can be smoothed using this setting.
This option defines whether or not a UVW tag should be created (the OBJ file must contain UVW coordinates).
Use this setting to define if and how the objects to be imported should be structured. If multiple objects are created they will all be placed under a single Null object.
All polygonal objects will be combined into a single object mesh. Different materials will be assigned via polygon selections. When importing splines, al splines will be combined as spline segments in a single spline.
Each object defined as such in the OBJ file (these are named "o" in the OBJ file) will also be imported as a separate object. When splines are imported, individual splines will be created.
Polygon groups defined in the OBJ file (these are named "g" in the OBJ file) will each be imported as a separate object.
Surfaces with the same material will be combined to a single object. Make sure select the correct option for the Material setting. If you do not allow *.mtl files to be read, the Splitting setting will be rendered useless.
If this option is enabled, polygon groups of the same name will be brought together as a single object.
Materials and texture paths in the OBJ format will be defined in a separate file (*.mtl). Here you can define if and how materials should be imported. Many times it’s important to correctly import the material assignments so they can subsequently be replaced by other/better materials (the material channels cannot be transferred loss-free).
Imported materials will be assigned directly via Material tag (UVW projection) an, if necessary, with the help of Polygon Selection tags. This is done in the following ways:
No *.mtl files will be read and no materials will be imported.
One material is created per imported object (the material color can be affected using the Default Material setting described below).
Enable this option if the corresponding *.mtl file should also be loaded. Materials and textures will, for the most part, be imported as they are in the source file.
If no *.mtl file (or object with no materials) is found, the Default Material setting will define the material colors.
Only the material names and polygon assignments in the OBJ file will be imported. Corresponding material properties (color, textures, etc.) will not be imported. The materials created will assume the color defined by the Default Material setting.
If Material is set to One default per object, you can define which color the material should have:
- White: a bright white
- Random Colors: Each imported material will be assigned a random color. With this option it is, for example, easy to determine how the objects are broken down.
When textures are imported, this selection menu defines how the Mix Mode (e.g., in the Color channel) will be set in each material channel. The default setting is Normal.
The purpose for this selection menu: Programs such as Maya set the color in the respective channels to black if textures are used. The OBJ specification also defines the mix mode Multiply. In spite of the texture, both of these combined would be black in Cinema 4D. The Normal setting would make the texture visible.
Enabling this option might help if odd effects occur with regard to transparencies upon import (the material is too transparent or completely transparent when imported). It can occur that an application outputs transparencies inversely or interprets them so. If this option is enabled, the Transparency channel’s Brightness will be inverted (if 90% is defined in the OBJ file, Cinema 4D will define 10%). With this option disabled, 90% will also be defined in the Transparency channel.
Flip X Axis
Flip Y Axis
Flip Z Axis
Swap X and Y Axes
Swap X and Z Axes
Swap Y and Z Axes
The OBJ format always assumes object axes from the world origin. Other object poitions or orientations in the OBJ file are achieved only via object point positions. Once such a file is imported it can be modified as usual (the 
Axis Center...
Since the OBJ format is such a commonly used format and different applications use different axis systems (with almost any imaginable axis combination, even with the Y axis pointing to the rear), these settings let you adjust the axes accordingly.
When importing certain OBJ files, for example, an object can literally be stood on its head. Enabling the Flip Y Axis option can prevent this from happening. Or you can switch the X and Y axes when exporting to a particular application because it has a different axis system. To do so, simply enable the Swap X and Y Axes option.
If this option is enabled, all polygon Normals will be flipped upon import/export.
If this option is enabled, all UV coordinates will be rotated 180° upon import/export.
Lines in the OBJ file correspond to the Linear spline Type in Cinema 4D and will also be imported as such by default.
The Splitting setting described above defines how the line segments are organized (whether as separate splines or as a single spline). The following options are available:
The lines will be imported as splines. Depending on the OBJ file, open contours can result with the last spline segment being open. If this is the case, use the next option.
The spline will always be imported with the Close Spline option enabled, i.e., the spline segments will always be closed. The first and last points will be connected. If spline start and end points lie on top of each other, the 
Optimize...
A polygonal object made up of triangles will be created from each polyline. This works best with polylines that lie on a single plane and, ideally, form a closed outline. This produces the best shapes.
If this option is enabled, a range of information will be output in the Console. Included is information about number of points or objects imported, object names, polygon count per object, how long the import took and so on.