Autodesk Forge Viewer Geolocation扩展坐标转换异常技术问询

Problem Context #

I'm working on placing marker objects on a Revit-created model using drone survey data, with access to high-precision GPS coordinates and omega/phi/kappa rotation data. When attempting to convert latitude/longitude/altitude data to Viewer space via the Autodesk.Geolocation extension, I've encountered critical issues:

• The calculated refPointLMV and GlobalOffset values are incorrect. For example, a selected point [0] on the model has a massive deviation from its real-world GPS coordinates, and refPointLMV returns an abnormally large value.
• Using GPS data from drone photos (e.g., (4.586577106, 51.626037158, 49.095), which is close to the model's positionLL84) with Geolocation.lonLatToLMV results in points completely outside the visible Viewer area.

We've submitted a support ticket (ID: LMV-5261) to Autodesk over two months ago, but progress has been minimal. The support team mentioned their engineering team is busy and suggested we implement a temporary fix on our end.

Temporary Hack (Single-Model Only) #

I've managed to adjust the conversion results to fit the Viewer space with the following code, but this only works for one specific model and won't scale to future models or drone datasets:

const gpsPosition = new THREE.Vector3(longitude, latitude, altitude);
const position = viewer
 .getExtension('Autodesk.Geolocation')
 .lonLatToLmv(gpsPosition);
const data = viewer.model.getData();
const globalOffset = data.globalOffset;
const refPointTransform = data.refPointTransform;
// Apply base transforms
position.add(globalOffset)
position.applyMatrix4(refPointTransform);
// HACK: Final -45 degree rotation to align points correctly
// Tested with 20+ drone photos, matches perfectly for this model
const quaternion = new THREE.Quaternion().setFromEuler(
 new THREE.Euler(0, 0, -Math.PI / 4),
 );
position.applyQuaternion(quaternion);

Questions #

1. When can we expect the Autodesk engineering team to fix this Geolocation extension issue?
2. Is this issue actually scheduled for a fix, or should we plan for a permanent custom solution?

Expert Response #

I totally get how frustrating this must be—relying on a core extension for critical geospatial alignment only to hit a wall with unresolved support tickets and a fragile hack that doesn't scale. Let's break down what we know and what you can do:

• Official Fix Timelines: Autodesk rarely publishes specific timelines for individual bug fixes, as their engineering priorities are based on factors like widespread user impact, severity, and resource availability. Since your ticket has been open for two months with limited updates, it's worth following up with the support team again—emphasize the business impact (e.g., blocked drone survey integration, multi-project scalability issues) to help elevate the priority of your request.

• Verify Model Geospatial Setup: Before assuming the issue is purely with the extension, double-check your model's geolocation configuration in Revit and during export/upload. Mismatched coordinate systems, incorrect datum references, or misconfigured north orientations can easily throw off the Geolocation extension's calculations. For example, ensure your Revit model's project north aligns correctly with the GPS data's true north, as this could explain the need for that -45° rotation hack.

• Build a Scalable Custom Conversion: If the official fix is delayed, you can create a more robust solution by calibrating with known control points. Pick 2-3 points that have both accurate GPS coordinates and clear Viewer model positions, then calculate a custom transformation matrix (translation, rotation, scaling) that maps GPS coordinates to Viewer space. This approach will work across different models as long as you repeat the calibration step for each new project.

• Alternative Workflows: If possible, explore exporting your model with geospatial data pre-aligned using tools like Navisworks or Civil 3D before uploading to the Viewer. Sometimes preprocessing the model's geolocation can bypass issues with the Autodesk.Geolocation extension entirely.

While there's no guarantee on when (or if) this specific bug will be fixed, taking proactive steps to validate your setup and build a scalable custom solution will help you avoid being blocked long-term.

内容的提问来源于stack exchange，提问作者Lewy Blue