# Dimensions

All point data in PDAL is stored as a set of dimensions. Dimensions have a name and a data type. The data type is determined at runtime, but a default data type for each dimension is listed below, along with the name of the dimension and its description.

The following table provides a list of known dimension names you can use in Filters, Writers, and Readers.

Note

Types are default types. Stage developers should set the dimension type explicitly if the default dimension isn’t suitable.

Name | Type | Description
--- | --- | ---
Alpha | uint16 | Alpha
Amplitude | float | This is the ratio of the received power to the power received at the detection limit expressed in dB
Anisotropy | double | Anisotropy of a point; larger values indicate strong variance in multiple dimensions.
Azimuth | double | Scanner azimuth
BackgroundRadiation | float | A measure of background radiation.
Blue | uint16 | Blue image channel value
ClassFlags | uint8 | Class Flags
Classification | uint8 | ASPRS classification. 0 for no classification. See LAS specification for details.
ClusterID | int64_t | ID assigned to a point by a point-clustering algorithm.
Coplanar | uint8 | Indicator of whether or not a point is part of a coplanar neighborhood.
Curvature | double | Curvature of surface at this point
DemantkeVerticality | double | Verticality of a point; larger values indicate vertical structure (Demantke’s variation).
Density | double | Estimate of point density
Deviation | float | Difference between the shape of the reference pulse and the return pulse. A larger value for deviation indicates larger distortion.
EchoRange | double | Echo Range
EdgeOfFlightLine | uint8 | Indicates the end of scanline before a direction change with a value of 1 - 0 otherwise
Eigenentropy | double | Eigenentropy of a point; small values indicate more ordered regions, while large values indicate disorder.
Eigenvalue0 | double | Smallest eigenvalue obtained form covariance of XYZ coordinates in k-neighborhood.
Eigenvalue1 | double | Middle eigenvalue obtained form covariance of XYZ coordinates in k-neighborhood.
Eigenvalue2 | double | Largest eigenvalue obtained form covariance of XYZ coordinates in k-neighborhood.
EigenvalueSum | double | Sum of computed eigenvalues.
ElevationCentroid | double | Elevation Centroid
ElevationHigh | double | Elevation High
ElevationLow | double | Elevation Low
Flag | uint8 | Flag
GpsTime | double | GPS time that the point was acquired
Green | uint16 | Green image channel value
HeightAboveGround | double | Height Above Ground
Infrared | uint16 | Infrared
Intensity | uint16 | Representation of the pulse return magnitude
InternalTime | double | Scanner’s internal time when the point was acquired, in seconds
IsPpsLocked | uint8 | The external PPS signal was found to be synchronized at the time of the current laser shot.
LatitudeCentroid | double | Latitude Centroid
LatitudeHigh | double | Latitude High
LatitudeLow | double | Latitude Low
Linearity | double | Linearity of a point; larger values indicate more linear regions.
LocalOutlierFactor | double | Outlier factor based on the LocalReachabilityDistance of a point’s nearest neighbors.
LocalReachabilityDistance | double | Reachability metric based on the NNDistance of a point’s nearest neighbors.
LongitudeCentroid | double | Longitude Centroid
LongitudeHigh | double | Longitude High
LongitudeLow | double | Longitude Low
LvisLfid | uint64 | LVIS_LFID
Mark | uint8 | Mark
Miniball | double | Metric capturing distance from a point to the center of the smallest enclosing ball encapsulating k-nearest neighbors, scaled by radius of the ball.
NNDistance | double | Distance metric related to a point’s nearest neighbors.
NormalX | double | X component of a vector normal to surface at this point
NormalY | double | Y component of a vector normal to surface at this point
NormalZ | double | Z component of a vector normal to surface at this point
NumberOfReturns | uint8 | Total number of returns for a given pulse.
OffsetTime | uint32 | Milliseconds from first acquired point
Omit | uint8_t | Used to shallowly mark a point as being omitted without removing it
Omnivariance | double | Omnivariance of a point; cube root of the product of all eigenvalues.
OptimalKNN | uint64 | Optimal number of k nearest neighbors, such that eigenentropy is minimized.
OptimalRadius | double | Radius corresponding to optimal k nearest neighbors, such that eigenentropy is minimized.
OriginId | uint32 | A file source ID from which the point originated. This ID is global to a derivative dataset which may be aggregated from multiple files.
PassiveSignal | int32 | Relative passive signal
PassiveX | double | Passive X footprint
PassiveY | double | Passive Y footprint
PassiveZ | double | Passive Z footprint
Pdop | float | GPS PDOP (dilution of precision)
Pitch | float | Pitch in degrees
Planarity | double | Planarity of a point; larger values indicate more planar regions.
PlaneFit | double | Metric capturing current point’s point to plane distance compared to those in the same k-neighborhood used to estimate the plane.
PointId | uint32 | An explicit representation of point ordering within a file, which allows this usually-implicit information to be preserved when reordering points.
PointSourceId | uint16 | File source ID from which the point originated. Zero indicates that the point originated in the current file
PulseWidth | float | Laser received pulse width (digitizer samples)
RadialDensity | double | Estimate of radial point density
Rank | uint8 | Estimated rank of neighborhood of points.
Reciprocity | double | Metric capturing percentage of k-nearest neighbors that also contain the current point in their k-neighborhood.
Red | uint16 | Red image channel value
Reflectance | float | Ratio of the received power to the power that would be received from a white diffuse target at the same distance expressed in dB. The reflectance represents a range independent property of the target. The surface normal of this target is assumed to be in parallel to the laser beam direction.
ReflectedPulse | int32 | Relative reflected pulse signal strength
ReturnNumber | uint8 | Pulse return number for a given output pulse. A given output laser pulse can have many returns, and they must be marked in order, starting with 1
Roll | float | Roll in degrees
ScanAngleRank | float | Angle degree at which the laser point was output from the system, including the roll of the aircraft. The scan angle is based on being nadir, and -90 the left side of the aircraft in the direction of flight
ScanChannel | uint8 | Scan Channel
ScanDirectionFlag | uint8 | Direction at which the scanner mirror was traveling at the time of the output pulse. A value of 1 is a positive scan direction, and a bit value of 0 is a negative scan direction, where positive scan direction is a scan moving from the left side of the in-track direction to the right side and negative the opposite
Scattering | double | Scattering of a point; larger values incidate complex (scattered) 3D regions.
ShotNumber | uint64 | Shot Number
StartPulse | int32 | Relative pulse signal strength
SurfaceVariation | double | Surface variation of a point; larger values indicate higher surface variation.
TextureU | double | U component of a texture location at this point
TextureV | double | V component of a texture location at this point
TextureW | double | W component of a texture location at this point
UserData | uint8 | Unspecified user data
Verticality | double | Verticality of a point; larger values indicate vertical structure.
W | double | W coordinate
WanderAngle | double | Wander Angle
X | double | X coordinate
XBodyAccel | double | X Body Acceleration
XBodyAngRate | double | X Body Angle Rate
XVelocity | double | X Velocity
Y | double | Y coordinate
YBodyAccel | double | Y Body Acceleration
YBodyAngRate | double | Y Body Angle Rate
YVelocity | double | Y Velocity
Z | double | Z coordinate
ZBodyAccel | double | Z Body Acceleration
ZBodyAngRate | double | Z Body Angle Rate
ZVelocity | double | Z Velocity