@allmaps/analyze

This module analyzes warpedMaps: it checks them for possible error and computes accuracy measures.

A Warped Map is an object used in @allmaps/render to store information about a georeferencedMap (which in turn are parsed Georeference Annotations) as it is warped by a transformer in order to be rendered. Hence, these objects have a lot of information that can e used to infer the quality and accuracy of a map’s warping.

In a WebGL2Renderer a map is warped and triangulated, so the TriangulatedWarpedMaps is used, which extends WarpedMaps.

How it works

This packages analyzes maps to return information, warning and error items. These items are objects with a code and text attribute, and possible additional information.

• Infos are notable but not problematic informations on a warping.
  • Code maskequalsfullmask: The mask contains the full image.
• Warnings are possibly problematic findings, but don’t invalidate the map.
  • Code gcpincompleteresource: A GCP has incomplete source coordinates.
  • Code gcpincompleteregeo: A GCP has incomplete source coordinates.
  • Code gcpoutsidemask: A GCP is outside the mask.
  • Code maskpointoutsidefullmask: A mask point is outside the full mask.
  • Code triangulationfoldsover: The map folds over itself, for the selected transformation type.
  • Code polynomialsheartoohigh: A polynomial transformation shows a shear higher then a set maximum.
• Errors are problematic findings that invalidate the map.
  • Code gcpamounttoolow: There are less then 3 GCPs.
  • Code gcpresourcerepeatedpoint: GCP resource coordinates are repeated.
  • Code gcpgeorepeatedpoint: GCP geo coordinates are repeated.
  • Code masknotring: The mask is not a valid ring (an array of points).
  • Code maskrepeatedpoint: Mask resource coordinates are repeated.
  • Code maskselfintersection: The mask self-intersects.

An analyzer can also compute the following Measures:

• About the current transformation type:
  • rmse: The root-mean-square error of GCPs in projected geo coordinates
  • destinationErrors: for each GCP, the error in projected geo coordinates
  • resourceErrors: for each GCP, the error in projected geo coordinates, scaled to resource space
  • resourceRelativeErrors: for each GCP, the error in projected resource coordinates, relative to the resource mask BBox diameter.
• About the Helmert transformation type:
  • helmertRmse: The root-mean-square error of GCPs in projected geo coordinates
  • helmertParameters: The Helmert parameters. See @allmaps/transform.
  • helmertScale: The scale
  • helmertRotation: The rotation
  • helmertTranslation: The translation
• About the polynomial transformation type:
  • polynomialRmse: The root-mean-square error of GCPs in projected geo coordinates
  • polynomialParameters: The polynomial parameters. See @allmaps/transform.
  • polynomialScale: The scale
  • polynomialRotation: The rotation
  • polynomialShear: The shear
  • polynomialTranslation: The translation

An analyzer can also compute the following Distortion information:

• About the current transformation type:
  • meanDistortions: For each computed distortion measure, the mean distortion over all triangulation points.

Installation

This is an ESM-only module that works in browsers and Node.js.

Install using npm:

npm install @allmaps/analyze

Usage

First, get a warpedMap, either by making it from an annotation, or by getting it from a renderer’s warpedMapList. Then analyze it using this library.

import { parseAnnotation } from '@allmaps/annotation'
import { TriangulatedWarpedMap } from '@allmaps/render'
import { Analyzer } from '@allmaps/analyze'

// Fetch an annotation
const annotation = await fetch(annoationUrl).then((response) => response.json())

// Create a warpedMap from the annotation
const georeferencedMaps = parseAnnotation(annotation)
const georeferencedMap = georeferencedMaps[0]
const triangualtedWarpedMap = new TriangulatedWarpedMap(
  georeferencedMap.id,
  georeferencedMap
)

// Or add the annotation the a renderer and extract a warpedMap
// ... create a webGL2Renderer, see the render package
await renderer.addGeoreferenceAnnotation(annotation)
const triangulatedWarpedMap = renderer.warpedMapList.getWarpedMaps()[0]

// Create Analyzer for the warpedMap
const analyzer = new Analyzer(triangulatedWarpedMap)

// Analyze to get all infos, warnings and errors
const infos = analyzer.getInfos()
const warnings = analyzer.getWarnings()
const errors = analyzer.getErrors()

// Or quickly check e.g. if there are any errors
const hasErrors = analyzer.hasErrors()

// Analyze measures and distortions
const measures = analyzer.getMeasures()
const distortions = analyzer.getDistortions()

API

Table of Contents

• Analyzer
  • Parameters
  • hasInfos
  • hasWarnings
  • hasErrors
  • getInfos
  • getWarnings
  • getErrors
  • getMeasures
  • getDistortions
  • fromWarpedMap
    • Parameters

Analyzer

Class for Analyzer. This class describes how a georeferenced map is warped using a specific transformation.

Parameters

• warpedMap A Warped Map
• mapId ID of the map

hasInfos

Check if analysis has infos.

Returns boolean

hasWarnings

Check if analysis has warnings.

Returns boolean

hasErrors

Check if analysis has errors.

Returns boolean

getInfos

Get analysis informations.

Returns Array<AnalysisItem>

getWarnings

Get zis warnings.

Returns Array<AnalysisItem>

getErrors

Get analysis errors.

getMeasures

Get analysis measures.

getDistortions

Get distortions.

Returns Distortions

fromWarpedMap

Creates an instance of Analyzer from a Warped Map.

Parameters

• warpedMap A Warped Map