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glass.sqdaitools

glass.sqdaitools is a toolkit for the whole GLASS data lifecycle: query products from the GLASS archive, map your region of interest onto the h<h>v<v> sinusoidal tiling, expand a date range into composite DOY folders, batch-download with resume + size verification, and post-process granules with terra (fill values, scaling, reprojection, multi-tile mosaics, temporal composites).

中文简介:glass.sqdaitools 是 GLASS(Global Land Surface Satellite)数据 全流程工具包:查询产品登记表、把研究区映射到正弦投影 h/v 瓦片、日期区间转 合成 DOY 文件夹、支持断点续传与大小校验的批量下载,以及基于 terra 的后处理 (填充值、比例因子、重投影、多瓦片镶嵌、时间合成)。中文快速上手: 《快速上手(中文)》。

Installation 

# install.packages("devtools")
devtools::install_github("GISerDaiShaoqing/glass.sqdaitools")

Quick start

1. Which tiles does my study area need? 

tiles <- glass_tiles_for_bbox(120.8, 30.6, 122.2, 31.9)  # Greater Shanghai
tiles

h/v are the sinusoidal tile indices used directly in GLASS file names (e.g. h28v05). For a polygon/multipolygon study area use glass_tiles_for_sf(roi).

2. What products and variants exist? 

glass_registry("LAI", verified_only = TRUE)

The registry bundles the archive’s directory structure for 133 variants (product × source × resolution), covering four archive layouts (year/DOY folders, year-level files, daily YYYYDDD folders and static file collections). 131 of them are verified against real granules — including file-naming fragments, composite cadence and band metadata (fill value, scale factor, valid range) used in the post-processing step.

3. Which composite folders cover my date range? 

glass_doys("LAI_MODIS_250M", from = "2018-08-01", to = "2018-12-31")

mode = "span" keeps every composite overlapping the range (default); mode = "start" keeps only composites that start inside it — the semantics of the typical legacy scripting workflow.

4. One-shot fetch (list + download) 

files <- glass_fetch(
  "LAI_MODIS_250M",
  from = "2018-08-01", to = "2018-12-31",
  tiles = "h28v05",
  out_dir = "data/glass/lai"
)

Downloads are retried, size-checked against the server, and can resume from a partial .part; a glass_manifest.csv ledger is written into out_dir. Set dry_run = TRUE to preview the manifest first.

5. Post-process to your region 

mean_lai <- glass_process(
  files,
  roi = roi_sf,        # your study area (sf); its CRS is the target CRS
  product = "LAI_MODIS_250M",
  fun = "mean",        # temporal mean over all composite layers
  outfile = "glass_lai_mean.tif"
)

glass_process() fills raw values (255 → NA, scaled correctly), groups granules by composite date, mosaics tiles per date, reprojects, crops/masks to roi, and can collapse layers with a function — the whole pipeline of a typical GLASS post-processing script, parameterised.

6. Interactive download UI

Draw your ROI on a Leaflet map (toggle roam/draw with one button, click twice to frame a rectangle), pick a verified variant and dates, preview the manifest, then download in one click — with an in-page directory browser for the output folder (no native dialog, works inside RStudio’s Viewer pane) and a per-file progress bar. After a download finishes, the map header can overlay a downsampled preview of the granules on the basemap (registry-driven fill/scale, multi-tile mosaics, ROI crop, webmerc output, palette + opacity controls), and previously downloaded data can be brought in without re-downloading via the Scan Import folder picker. Requires shiny and leaflet; the directory browser additionally uses shinyFiles.

GUI front end: D3L Tool

Prefer a desktop application? D3L Tool (online docs) is a NASA satellite download manager. Its v2.7.0 release integrates GLASS batch downloading built on the skeleton of this package, while granule post-processing (fill values, mosaics, reprojection, temporal composites) keeps running on glass.sqdaitools. The two projects are designed as a matched pair: D3L Tool for interactive search & download, glass.sqdaitools for reproducible, scriptable processing.

Acknowledgements

Data are publicly hosted by the GLASS product team (glass.hku.hk). Please respect their citation policies; the package only reads public directory listings.

Author

Shaoqing Dai · ORCID 0000-0003-0858-4728 · Homepage · GitHub