Geoscience Objects

Version: 1.0.0

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variogram

schema/objects/experimental-variogram/1.0.0/experimental-variogram.schema.json

See also: variogram (fitted model counterpart).

Overview

The experimental-variogram object is used to capture spatial variability of univariate data across an area of interest. Spatial variability is described by direction and summarized per each lag in a direction.

The experimental variogram is calculated a part of a standard variography workflow and is precursor to variogram modeling. An experimental variogram is a key input to fitting a variogram model.

Required Data

To construct an experimental variogram object the following information is required.

• data_variance (number): The variance of the source data

• directions (object): Table describing geometry and type of each direction for which lags exist.

  • data (binary blob): Table with columns: offset, count, direction_type, azimuth, dip, azimuth_tolerance, dip_tolerance, bandwidth, bandheight.
    • offset (integer): Index in the lags table at which the information associated with this direction begins
    • count (integer): Number of entries in lag tabl associated with this direction (number of lags).
    • direction_type (string: ["directional", "omnidirectional" or "downhole"]): type of direciton described
    • azimuth (float): Clockwise rotation about the z-axis
    • dip (float): Incline of the direction, negative points down
    • azimuth_tolerance (float): Tolerance considered on either side of the azimuth direction, contributing to the conical definition of the search
    • dip_tolerance (float): Tolcerance considered on either side of the dip, contributing to the conical definition of the search
    • bandwidth (float): Width of the search to be considered once the conical search has reached its extexts
    • bandheight (float): Height of the search to be considered once the conical search has reached its extexts
  • length (integer): Number of directions
  • width (const): Must be 9
  • data_type (const): Must be "uint64/uint64/string/float64/float64/float64/float64/float64/float64"

• lags (object): Table describing individual lags

  • data(binary blob): Table with columns: start, end, centroid, value, num_pairs.
    • start (float): start distance of the lag
    • end (float): end distance of the lag
    • centroid (float): average distance (centroid) of all pairs represented in lag
    • value (float) : calculated value representing spatial correlation, semi-variance or other described by the variogram_type field.
    • num_pairs (integer): number of pairs considered in the value calculation.
  • length (integer): Total number of lag bins
  • width (const): Must be 5
  • data_type (const): Must be "uint64/uint64/float64/float64/float64/float64/uint64"
  • directions (object): Contains:

Example Tables

Two small examples below demonstrate the defined format of the directions and lags tables described above.

Directions Table

offset	count	direction_type	azimuth	dip	azimuth_tolerance	dip_tolerance	bandwidth	bandheight
0	20	directional	0	0	22.5	22.5	50	50
20	20	directional	90	0	22.5	22.5	50	50
40	20	directional	0	-90	10.0	10.0	20	20

Lags Table

start	end	centroid	value	num_pairs
0.0	5.0	2.5	0.012993	33
5.0	10.0	7.5	0.160659	63
10.0	15.0	12.5	0.313465	12
15.0	20.0	17.5	0.422976	43
20.0	25.0	22.5	0.502526	74

Optional fields include:

• description (string)
• domain (string): The domain the variogram is calculated for
• attribute (string): The attribute the variogram is calculated for
• variogram_type (string, default: "variogram"): Type of calculation performed Both lags and directions can also have optional additional attributes through the attribute-list-property component.
• distance_unit (string): Distance units used to describe start, end and centroid in lag table
• attribute_unit (string): Units of the attribute being described

The schema enforces unevaluatedProperties: false, meaning no additional properties beyond those defined are allowed.

Properties

experimental-variogram (v1.0.0)

An experimental variogram object representing spatial continuity statistics for a single variable, grouped by direction and lag distance.

Property	Type	Description	Flags
name	String	Name of the object.	⬆️ ✅
uuid	base-object-properties	Identifier of the object.	⬆️ ✅
description	String	Optional field for adding additional description to uniquely identify this object.	⬆️
extensions	Object	Extended properties that may be associated to the object, but not specified in the schema	⬆️
tags	Object	Key-value pairs of user-defined metadata	⬆️
lineage	lineage	Information about the history of the object	⬆️
schema	String		✅
domain	String	The domain the experimental variogram is calculated for.
attribute	String	The attribute the experimental variogram is calculated for.
data_variance	Number	The variance of the source data, often used as the expected sill of the variogram.	✅
variogram_type	String	The type of calculation performed (e.g., variogram, semi-variogram, covariance, correlogram).
distance_unit	unit-length	Distance unit.
attribute_unit	unit	Attribute unit
directions	experimental-variogram	A data-table defining the parameters for each variogram direction.	✅
lags	experimental-variogram	A data-table containing the calculated values for each lag bin.	✅

Legend

Flag	Description
⬆️	Inherited property
✅	Required property