Modern, click-anywhere RF coverage viewer built on SPLAT!
Open a browser, drop a transmitter pin anywhere in the contiguous US, pick a band (FRS / GMRS / MURS / 2 m / 70 cm / UHF-TV / …) and an antenna preset, and see the real-terrain signal-strength contours overlaid on an OpenStreetMap basemap. Backed by SPLAT! 1.4.2's ITWOM propagation engine + 1-arc-second SRTM terrain auto-fetched on demand.
Built around three pieces that talk to each other through plain files:
- SPLAT! HD (the original C++ engine, ported here to Windows
MSVC / CMake / vcpkg) reads a
.qth(TX location + height), a.lrp(radio params + ERP), and SRTM-derived.sdfterrain tiles, then writes a coverage map as PNG or GeoTIFF (Phase 2 and Phase 3 added these alongside the legacy PPM output). - A static-file + JSON server (viewer/launch.ps1)
that turns POSTed form data into
.qth+.lrp, invokes SPLAT!, and serves the result. It auto-fetches missing SRTM tiles from the public AWS Mapzen Skadi mirror through utils/fetch_srtm.ps1. - A Leaflet front-end (viewer/index.html) that lets you click-to-place a TX, pick band / antenna / power presets, and overlay the resulting georeferenced PNG on an OSM basemap with an opacity slider.
So you get a workflow like:
click map → POST /compute → fetch SRTM tiles → write qth+lrp →
splat-hd → png+geo → overlay refreshes on basemap
# 0. Prereqs (one-time): Visual Studio Build Tools 2022 (C++ workload),
# vcpkg bootstrapped at $env:USERPROFILE\vcpkg.
# 1. Build everything (std splat for tests, HD splat for interactive,
# plus the srtm2sdf converter).
$env:VCPKG_ROOT = "$env:USERPROFILE\vcpkg"
cmake -S . -B C:\splat-build -G "Visual Studio 17 2022" -A x64 -DSPLAT_BUILD_UTILS=ON
cmake --build C:\splat-build --config Release --target srtm2sdf-hd
cmake -S . -B C:\splat-build-hd -G "Visual Studio 17 2022" -A x64 -DSPLAT_HD_MODE=1 -DSPLAT_MAXPAGES=9
cmake --build C:\splat-build-hd --config Release --target splat
# 2. Launch the viewer. SRTM tiles get cached in -SourceDir on first
# click in each new region (~6 min); subsequent clicks reuse them.
mkdir C:\splat-work
copy sample_data\wnju-dt.qth C:\splat-work\ # any TX for the initial preview
copy sample_data\wnju-dt.lrp C:\splat-work\
.\viewer\launch.ps1 -SourceDir C:\splat-workBrowser opens at http://localhost:8765/. Click anywhere in the
contiguous US, pick band + antenna + power, hit Compute coverage,
wait for terrain to download (first time per region) + SPLAT! to run.
If PowerShell complains about execution policy on first launch:
Set-ExecutionPolicy -Scope CurrentUser RemoteSigned.
See viewer/README.md for the full interactive-viewer docs (the HTTP API, options, screenshots, etc.).
.
├── CMakeLists.txt ← top-level build (replaces upstream bash
│ configure + build, supports MSVC + GCC)
├── cmake/Dependencies.cmake ← find_package wrappers for bzip2, zlib, tiff
├── vcpkg.json ← dependency manifest for vcpkg
├── src/ ← splat sources (moved here from project root)
│ ├── splat.cpp ← the engine + the 4 image writers (refactored
│ │ to emit PPM / PNG / GeoTIFF behind a unified
│ │ per-pixel-color dispatch path)
│ ├── itwom3.0.cpp ← propagation physics (untouched)
│ ├── compat/ ← Windows portability shims (unistd/mkstemp/...)
│ ├── render/ ← Image + PngWriter + GeoTiffWriter (Phase 2-3)
│ └── third_party/ ← vendored stb_image_write.h
├── utils/ ← srtm2sdf (ported to Windows) + others
│ └── fetch_srtm.ps1 ← public SRTM tile fetcher
├── viewer/ ← Leaflet front-end + PowerShell HTTP server
│ ├── index.html
│ ├── launch.ps1
│ ├── README.md ← full viewer docs
│ └── screenshots/
├── tests/ ← regression harnesses
│ ├── run_golden.ps1 ← Tier-1: text path-report SHA-256
│ ├── run_image_golden.ps1 ← Tier-2: 4 image writers x 3 formats
│ └── inspect_geotiff.ps1 ← pure-PS GeoTIFF tag inspector
├── sample_data/ ← upstream WNJU-DT sample inputs (unchanged)
├── docs/ ← upstream SPLAT! documentation
├── README ← original SPLAT! 1.4.2 README (preserved)
├── CHANGES ← original SPLAT! 1.4.2 changelog (preserved)
└── COPYING ← GPL v2 license text (this is GPL too)
In commit-history order — each step has a regression net behind it
(tests/run_golden.ps1 text reports, tests/run_image_golden.ps1
4-variant × 3-format image gates):
| # | Phase | What it added |
|---|---|---|
| 1 | Cross-platform | CMake + vcpkg replace the bash ./configure + interactive prompts. Builds on MSVC, gcc, clang. |
| 1 | DEM heap refactor | The multi-GB compile-time-sized static arrays became heap-allocated pointer-to-row buffers — required for MSVC (no -mcmodel=medium), zero call-site changes. |
| 1 | 3 porting bug fixes | assert((s=new ...)) side effect lost in Release; MSVC stack default too small for the ITWOM call chain; acos(1+ε) NaN in Distance() under /fp:fast. |
| 1 | SDF separator | Tile filenames switched from : (illegal on NTFS) to _ on Windows. |
| 2 | PNG output | New src/render/ module (vendored stb_image_write.h); all 4 image writers (topo/LR/SS/dBm) emit PNG alongside PPM, verified byte-identical (34.9 M pixels, 0 diffs). |
| 3 | GeoTIFF output | libtiff-backed GeoTIFF writer with EPSG:4326 georeferencing tags; recognized by QGIS / ArcGIS / GDAL / leaflet-geotiff. |
| 5 | Leaflet viewer | Static-overlay viewer with the PNG anchored to its .geo bounds. |
| 6 | Real terrain | Ported srtm2sdf to Windows; fetch_srtm.ps1 pulls 1-arc-second SRTM from public mirrors and converts to .sdf-hd. |
| 7 | Interactive form | Click-to-place TX + band / antenna presets + radio params + POST /compute endpoint that drives splat live. |
| 8 | Click anywhere | Auto-fetch fills in whatever SRTM tiles the click needs; AWS Mapzen Skadi mirror (more complete than ESA) is primary. |
- SPLAT! 1.4.2 by John A. Magliacane, KD2BD — the engine, the SRTM/USGS pipeline, the LRP propagation model. EasyProp is a derivative work and keeps SPLAT!'s GPL v2 license (see COPYING and the preserved README).
- ITWOM 3.0 by Sid Shumate — propagation physics.
- stb_image_write.h by Sean Barrett — public-domain single-header PNG writer (vendored under src/third_party/).
- libtiff via vcpkg — GeoTIFF.
- Leaflet + OpenStreetMap — basemap.
- AWS Mapzen Skadi + ESA SRTMGL1 — public SRTM mirrors.
GPL v2 (matching upstream SPLAT!). See COPYING.