In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Type Attributes), this format also adds format-specific attributes (Format Attributes).
FME AR assets (features) consist of geometry and geometry attributes. All FME AR assets have one predefined attribute, fmear_type, which identifies the type of the geometry. Geometry types are 3D (x,y,z), and fmear_face can contain texture and normal coordinates.
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Attribute Name |
Value |
|---|---|
|
fmear_type |
The type of geometry read from the table. This attribute will contain the fme_surface geometry type. Default: No default |
|
fmear_location_feature |
Can be set to either anchor or viewpoint. Values are case-sensitive.
|
Anchor
FME AR supports Anchor, a type of feature that provides additional information to the FME AR App on how to load the model. An FME AR Anchor may be geolocated, which relates the model to a location in the real world. An FME AR file may only have one anchor provided – anchors beyond the first will be rejected.
A Geolocated Anchor feature must have both the fmear_anchor_latitude and fmear_anchor_longitude attributes with numeric values in LL84 in order to be considered a geolocated anchor.
A non-geolocated Anchor is specified with a Point or Null geometry. If the Anchor feature has no geometry, the model center is used as the anchor point. Anchors may not have other types of geometry set. This type of Anchor is used to specify a specific attachment point in the scene – for example, the corner of a building instead of its center. It is also possible to specify a Z coordinate to change the effective ground level of the model – the value of the Anchor’s Z coordinate will be treated as the surface level when displaying the model. For example, writing a 10-storey building to FME AR along with an Anchor whose Z coordinate corresponds to the floor of the 4th level will cause the FME AR App to render the building where the 4th floor is flush with the display surface. Similarly, changing the Anchor’s Z coordinate so it corresponds with one of the underground parking levels will cause the FME AR App to render the building with that underground level flush with the detected surface.
A Geolocated Anchor may be combined with a non-geolocated Anchor to both correlate the model to a physical location and modify the model’s attachment point. They must be combined into a single feature to perform this function.
Anchor features will be checked for FME AR metadata attributes, but otherwise their attributes will not be written. Do not tag features with desired 3D geometry as an anchor. Rejected Anchors will not be checked for metadata. Anchors that reach the writer after the first valid anchor is found will be rejected. Avoid creating workspaces where more than one Anchor feature will be created.
|
Attribute Name |
Function |
|---|---|
|
fmear_anchor_latitude |
The latitude the model’s origin maps to in LL84. |
|
fmear_anchor_longitude |
The longitude the model’s origin maps to in LL84. |
Viewpoints
In order to be able to easily teleport between different points within a model, an FME AR file may contain a number of Viewpoints, which, when viewed with a supported app, allow users to recenter the view on them. This allows multiple points of interest on a model to be reached quickly.
A feature with the attribute fmear_location_feature set to viewpoint and containing a Point geometry will be recorded in the output file as a viewpoint. Features that have the attribute but are not points will cause a warning to be logged. Viewpoints may be specified with either 3D or 2D points. In the case of 2D, (Z = 0) will be assumed.
You can (optionally) name a viewpoint by using a GeometryPropertySetter transformer to set the geometry name.
Viewpoint features will be checked for FME AR metadata attributes, but otherwise their attributes will not be written. Viewpoint features with null geometries or a geometry type other than Point will be rejected. Rejected Viewpoints will not be checked for other metadata.
FME AR Metadata
FME AR supports certain metadata keys that will be written to the output file that can affect how the model is displayed. These values are specified as format attributes and each valid feature will be checked for these. Only the first value found for each individual key will be used and subsequent values will be ignored by the writer.
Model Expiration Date
When a model is meant to have a fixed lifetime, the fmear_model_expiry metadata attribute can be specified. The value must be expressed as an FME-format date in order to be considered valid. Other values will be logged and will not be used.
When the expiration date has passed (according to the mobile device’s system clock), a notification will be displayed that the model is no longer valid for use. For example, this can be used when an authorization to excavate near underground gas or power lines has been issued and the authorization has a fixed lifetime. A model’s expiration date can match the expiration of the authorization in this case.