VTPK (Vector Tile Package)

GISBox is a one-stop 3D GIS data editing, conversion and publishing platform that supports editing in multiple GIS formats such as OSGB/GEOTIFF/RVT, converting to 3DTiles/Terrain and publishing.

Introduction

VTPK (Vector Tile Package) is a vector tile data format proposed by Esri. It is built based on vector data compression and slicing technology. It realizes efficient storage and transmission by decomposing geospatial data into multi-level pyramid structured vector tiles (PBF format). Its core features include multi-resolution support, vector data-based compression algorithm, cross-platform compatibility and offline use capability. It is suitable for mobile navigation, geographic information collection, outdoor survey and other scenarios.

File Structure

Main image file (.sid)

Using discrete wavelet transform (DWT) technology, image data is decomposed into multiple resolution levels (image pyramid structure).
Each level corresponds to image data of different resolutions, forming a continuous transition from high resolution to low resolution, supporting progressive loading and seamless browsing.
The compression algorithm takes into account both high compression ratio (about 20:1 for grayscale images and about 50:1 for true color images) and image quality, ensuring clear details after decompression.

Coordinate file (.sdw)

Stores geospatial reference information (such as projected coordinate system, geodetic datum, etc.) to ensure that image data is accurately aligned with real geographic coordinates.
Supports linkage with the main image file to realize geographic positioning and spatial analysis functions.

Pros

Efficient compression and fast rendering: The compression algorithm based on vector data greatly reduces the file size, and the slicing technology is combined to achieve on-demand loading, which significantly improves the rendering performance, especially suitable for resource-constrained environments on mobile terminals.
**Offline availability and cross-platform compatibility: **Supports localized deployment and can be used in a network-free environment. It is also compatible with multi-platform GIS software, facilitating data sharing and transmission.
**Multi-resolution flexible interaction: **Smooth zooming is achieved through the pyramid structure, only visible area data is loaded, memory usage and loading speed are optimized, and dynamic interaction needs are met.

Cons

Complex static data updates: As snapshot files, VTPK update data needs to be regenerated, making it difficult to respond to dynamic changes in real time.
Limited dynamic rendering capabilities: Lack of deep support for real-time interaction and dynamic display, insufficient flexibility.
Large file storage pressure: VTPK files generated by large-scale data sets may still occupy a large storage space, and the compression ratio and data volume need to be weighed.

Application Scenario

It is suitable for GIS and mobile application scenarios that require fast loading and interactive display of vector maps (such as smartphone navigation, geographic information collection tools, outdoor adventure/survey and other offline scenarios).