Spatial data can look correct on screen while still being shifted, rotated or vertically inconsistent. In an Israeli project, a reliable workflow must preserve the source reference system and make every transformation reproducible.

Aerial illustration of an urban plaza with a coordinate grid and surveyed control point

*A visible overlay is not proof of correct coordinates. Control points make the transformation testable.*

Table of contents

Why this is difficult

The label “Israeli coordinates” does not describe every detail required to position data correctly. A dataset may use Israel TM Grid, a local engineering grid, geographic coordinates, a surveyor-defined origin or a model-space convention. Units, axis order, transformation parameters and height datum may be missing or recorded outside the file.

Different software packages also make different assumptions. A database may know an SRID while a mesh contains only local coordinates. BIM can use a project base point. Photogrammetry output can be georeferenced horizontally but use ellipsoidal or local heights. A browser globe ultimately displays an Earth-centered representation.

Separate source, storage and delivery

A resilient architecture treats three states separately:

  1. Source state — the original file, CRS declaration, units, datum, capture metadata and checksum.
  2. Canonical storage state — the database representation selected for querying and joining, with the original reference retained.
  3. Delivery state — the coordinates, tiling and precision strategy required by the web viewer or downstream application.

The source should not be overwritten merely because the viewer needs another representation. Derived products should record which source and transformation created them.

PostGIS can store geometry with an SRID and perform defined transformations. It does not repair an incorrect CRS label, recover a missing height datum or decide whether a local survey grid is equivalent to EPSG:2039. Those are project facts that must be supplied and verified.

An explicit transformation chain

A useful transformation record answers:

  • What is the declared source CRS?
  • Are the horizontal units metres?
  • What axis order does the source application use?
  • Is there a local-to-grid translation, rotation or scale?
  • Which transformation library and grid files were used?
  • What is the target CRS for storage and delivery?
  • Which control points test the result?

For web 3D, the chain may include source coordinates → EPSG:2039 → geographic longitude and latitude → Earth-centered Cartesian coordinates. Large local models may also use a local origin or high/low precision encoding to avoid floating-point jitter. Each step should be generated from parameters, not dragged into place by eye.

Height is its own reference system

Horizontal agreement does not prove vertical agreement. Elevations may be orthometric, ellipsoidal, relative to a site benchmark or simply local model heights. A constant vertical offset can make a layer appear underground or above the terrain even when eastings and northings are correct.

Record the height datum, geoid model, benchmark, units and any applied offset. If they are unknown, mark the vertical reference as unknown and require review. Do not hide uncertainty inside an undocumented Z correction.

Photogrammetry, BIM and 360

Photogrammetry should retain camera positions, control points, processing coordinate system and reconstruction reports. BIM needs its shared-coordinate or project-base-point relationship. A 360° route needs positions and orientations in the same spatial frame as the project.

When these sources are aligned, Skylens Viewer can move between a map, model and panorama without losing context. When they are not, the interface may still look polished while measurements and cross-layer selections are unreliable.

Acceptance tests

A spatial delivery should pass explicit tests before publication:

  • compare independent control points, not only points used during fitting;
  • report horizontal and vertical residuals separately;
  • inspect several areas across the project extent;
  • verify units, orientation and axis order;
  • compare known parcel, road or building boundaries;
  • test model-to-BIM and panorama-to-model alignment;
  • confirm repeatability by rebuilding from recorded parameters;
  • retain the result, software version and reviewer.

The acceptance threshold depends on the intended use. Marketing visualization, progress documentation, quantity calculation and engineering setting-out do not require the same accuracy. The declared fitness for purpose matters as much as the numeric residual.

Project intake checklist

Before processing begins, request the original files, declared CRS, survey report, control points, height datum, units, expected accuracy and intended use. Ask whether any manual offsets were already applied and whether a local grid exists.

If a critical field is missing, use UNKNOWN or REVIEW_REQUIRED. A guessed datum can produce a clean-looking but irreproducible system.

Frequently asked questions

Is setting EPSG:2039 in the file enough?

No. The label must describe the coordinates that are actually stored. Units, axis order, vertical reference and any local transformation still need verification.

Why can a model look correct on the map but fail against BIM?

The layers may use different origins, rotations, height references or levels of accuracy. A basemap comparison is often too coarse to reveal those differences.

Is Cesium the spatial database?

No. Cesium is a visualization and runtime environment. Authoritative entities, relationships, versions and provenance should remain in managed data services such as PostGIS and project storage.

What is the most important metric?

There is no universal single metric. Residuals against independent control, separated into horizontal and vertical components and judged against intended use, provide a defensible starting point.

Spatial accuracy is part of product quality

Correct coordinates are not a back-office detail. They determine whether measurement, comparison, BIM alignment and change analysis can be trusted. The best workflow preserves sources, documents transformations and makes uncertainty visible.

Explore Skylens 3D mapping services or contact us about an Israeli-grid project.