Mega fundamentals
Mega involves multiple key concepts and technical terms. These are core elements for building and using city-scale AR localization services. This document explains the main concepts in non-technical language, including EMP, Mega Block, EIF, and EMA. Understanding these concepts helps you better plan projects, acquire data, verify results, and optimize AR experiences.
EMP (mapping data)
EMP is the file format recorded when mapping data is acquired with a mobile phone. It contains video frames, IMU (inertial measurement unit) data, GNSS information, SLAM poses, and other data, and can be used to generate the corresponding mapping result, Mega Block.
Purpose
- Fast mapping: suitable for small spaces such as rooms and exhibition halls, or specific objects, without professional equipment.
- Complements panoramic camera data: EMP is more flexible.
How to obtain and use
- Obtain: use the Mega Toolbox App to slowly move the phone in the target area and record (see Acquiring small-area spaces with a mobile phone - acquisition method or Acquiring specific objects with a mobile phone - acquisition method), then export the EMP file.
- Use: upload it to the console, create a small-area mobile acquisition task or an object mobile acquisition task, and generate a Block.
Notes
- EMP files are relatively small and suitable for quick iteration, but they are not suitable for very large spaces.
- Acquisition key points: move slowly, scan from multiple angles, and avoid blur or dynamic interference; see the acquisition checklist.
- If EMP leads to low Block quality, check phone compatibility (ARCore/ARKit support is required).
Mega Block
Mega Block is the core localization map unit of Mega. A three-dimensional model and localization map are generated by the mapping service, containing the geometric structure, visual features, coordinate information, and other data of the target area. It is similar to a "digital twin map".
Features
- Provides high-precision localization: the device anchors centimeter-level world coordinates by matching the current camera image with features in the Block.
- Supports AR fusion: including occlusion between virtual and real content and persistent content.
- Coverage: a single Block can reach millions of square meters and supports multiple floors or large spaces.
How to obtain and use
- Obtain: upload data to the console through data acquisition, create a mapping task, and the Block is generated automatically.
- Use: create a localization service and localization library, add the Block to the localization library, and then configure it in the application.
Notes
- Block quality depends on acquisition data: Blocks generated from environments with rich features and uniform lighting usually perform best.
- For mapping troubleshooting, see mapping failure or model defects.
EIF (simulation data)
EIF is a data format used for simulated localization testing. It contains video frames, IMU (inertial measurement unit) data, GNSS information, SLAM poses, and other data, and is used as input for Mega services.
Purpose
- Simulation verification: replay EIF data on a computer to preview localization and tracking results without on-site testing.
- Issue reproduction: record abnormal segments to help debug tracking issues such as drift and loss.
- Effect preview: combine with annotation files to simulate AR content overlay and evaluate the final user experience.
How to obtain/use
- Obtain: record with Mega Toolbox in the target area (see Simulation effect preview - acquiring EIF data or Visual anomaly data collection - using Toolbox to record mobile EIF files), then export the EIF file.
- Use: import it into Mega Studio and replay it to view localization performance; or upload it when reporting an issue.
Notes
- The recorded EIF duration should not exceed 10 minutes. Excessive acquisition time affects device SLAM performance.
- It is used only for testing and not for production mapping.
EMA (annotation file)
EMA is the format of annotation data files, used to define the position, orientation, and behavior of AR content in a Mega Block. It is a JSON-like structured file that contains annotation information such as coordinate points, 3D model references, and trigger conditions.
Purpose
- Content anchoring: specify the exact real-world position where virtual objects, such as models, text, and animations, should appear.
- Interaction definition: set trigger rules, such as showing content when the user approaches, as well as animation logic, sound, and other behavior.
- Effect preview: combine with EIF or on-site testing to simulate a complete AR experience.
Notes
- EMA is optional: basic localization does not require EMA, but rich interactions do.
- If EMA causes content offset, check coordinate system consistency (matching the Block).
After understanding these concepts, you can use Mega services more efficiently. For deeper details, refer to the overview or specific chapters.