# 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. |

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. |

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. |

LongitudeCentroid |
double |
Longitude Centroid |

LongitudeHigh |
double |
Longitude High |

LongitudeLow |
double |
Longitude Low |

LvisLfid |
uint64 |
LVIS_LFID |

Mark |
uint8 |
Mark |

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. |

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) |

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 |