CesiumGS/cesium

Primitive with heightReference have a wrong positioning in 2D mode

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#12,531 opened on Mar 20, 2025

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 (4 comments) (1 reaction) (1 assignee)JavaScript (11,758 stars) (3,324 forks)batch import
good first issueonrampingtype - bug

Description

What happened?

Hello!

I use Cesium version 1.127.0. When a primitive has a heightReference other than NONE, its position on map is wrong in 2D mode. In 3D or without the heightReference, the primitive is placed properly.

If the primitive is displayed at lattitude longitude [0, 0], it is correctly placed.

Thank you for your help!

Sandcastle with option to add a point with a heightReference set to CLAMP_TO_GROUND

Reproduction steps

  1. Add two primitives (point or billboard) with and without a heightReference different than NONE
  2. Set the map in 2D mode
  3. The two primitives are not placed at the same position on map

Sandcastle example

https://sandcastle.cesium.com/#c=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

Environment

Browser: Chrome and Edge CesiumJS Version: 1.127.0 Operating System: Window 10 and 11

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptCesiumJS basicsCoordinate transformation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
The bug appears when primitives with heightReference other than NONE are displayed in 2D mode; they are mispositioned. Investigate how CesiumJS applies height offsets in 2D versus 3D rendering. The Sandcastle example can be used to reproduce. Likely the issue is in the transformation pipeline for 2D mode, possibly near the Cartesian to screen coordinate conversion. Check the Primitive class and related shader code. Since the issue is assigned, the assignee may already have insights.