# 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. |

BeamDirectionX |
double |
Beam direction unit vector X coordinate |

BeamDirectionY |
double |
Beam direction unit vector Y coordinate |

BeamDirectionZ |
double |
Beam direction unit vector Z coordinate |

BeamOriginX |
double |
Beam origin X coordinate of current laser shot |

BeamOriginY |
double |
Beam origin Y coordinate of current laser shot |

BeamOriginZ |
double |
Beam origin Z coordinate of current laser shot |

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. |

Dimension |
uint8 |
Dimension of the points. three types of dimensions are available (Linear : points form a linear feature. Planar : points form a planar surface. Complex : random group of points). |

DownPositionRMS |
double |
Down position RMS error |

DownVelocityRMS |
double |
Down velocity RMS error |

EastPositionRMS |
double |
East position RMS error |

EastVelocityRMS |
double |
East velocity RMS error |

EchoNorm |
double |
Difference in shape of a return signal compared to a typical return from a hard surface. |

EchoPos |
double |
Difference in position of a peak of a return signal compared to a typical return from a hard surface |

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 |

HeadingRMS |
double |
Heading RMS error |

HeightAboveGround |
double |
Height Above Ground |

Image |
uint16 |
Index of the image use for texturation. |

ImgNbr |
uint8 |
Stores the number of the image from which it gets the color. |

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 |

NorthPositionRMS |
double |
North position RMS error |

NorthVelocityRMS |
double |
North velocity RMS error |

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 |

PitchRMS |
double |
Pitch RMS error |

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 |

Reliability |
double |
Reliability (or confidence) of points |

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 |

RollRMS |
double |
Roll RMS error |

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 |