From 9310ddbe2aab41fce2f05a8de65ac5927075037a Mon Sep 17 00:00:00 2001
From: Mark Allyn <allyn@well.com>
Date: Sat, 23 May 2026 09:11:34 -0700
Subject: [PATCH] Add locations and terrain data

---
 CLAUDE.md | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/CLAUDE.md b/CLAUDE.md
index fb1b803..9e8b155 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -708,6 +708,22 @@ PPI Radar Equiation
    
    =====================================================================
 
+   Locations of the radars -
+
+   Chain Home : RAF Ventnor (Isle Of Wight) 
+      Decimal Degrees (Latitude / Longitude): 50.600° N, 1.183° W 
+
+   A Scope Marine - Anchored Boat at Community Boating Center (stays here, not moving around)
+      latitude \(48.70529^{\circ}\text{ N}\) and longitude \(-122.50547^{\circ}\text{ W}\)
+
+   PPI Marine Traffic Control - center of bellingham bay
+      latitude \(48^\circ 43' 25" \text{ N}\) and longitude \(122^\circ 34' 35" \text{ W}\) 
+
+   PPI Police Boat ( starts as docked at the taylor street dock; but will be moving around
+      48.735519° N latitude and -122.331931° W longitude.
+
+   =====================================================================
+
    Graticules - These are plastic overlays over the face of the scope. They are
    for the purposes of showing the bearing. They are calibrated in degrees; short line (1/8 inch)
    each degree; medium line (1/4 inch) for every 5 degrees; and a longer line (1/2 inch) for every
@@ -765,6 +781,61 @@ PPI Radar Equiation
 
    =======================================================================
 
+   GROUND TERRAIN AND LIDAR DATA PROCESSING
+
+   Note that the following files already exist in the project directory
+   in the following:
+
+   map
+   map/lidar_raw
+   map/lidar_raw/wa2016_west_dem_J1364939.zip
+   map/lidar_raw/wa2022_nooksack_dem_J1364940.zip
+   map/charts_enc
+   map/charts_enc/US5WA45M.000
+   map/charts_enc/n48_w123_1arc_v3.tif
+   
+   This needs to be processed into a fragment shader via ray casting.
+
+   Details on files:
+
+   US5WA45M.000 (ENC Chart): This is an Electronic Navigational Chart 
+       (S-57 format) specifically covering the Bellingham Bay and Harbor 
+       area. It contains vector data for the shoreline, docks, piers, 
+       and water depths (bathymetry), as well as navigational aids.
+
+   n48_w123_1arc_v3.tif (DEM): This is a USGS 1-arc-second Digital 
+       Elevation Model in GeoTIFF format. It provides a continuous grid of 
+       land elevation data for the area (roughly 30-meter resolution). 
+       This is your primary source for the broad terrain shape.
+
+   wa2022_nooksack...zip & wa2016_west...zip (LiDAR DEMs): These are 
+       high-resolution Digital Elevation Model zips from the Washington 
+       State LiDAR portal. They contain the incredibly detailed data for 
+       localized buildings, docks, and fine shoreline features that the 
+       30-meter USGS data misses.
+
+   Suggestion for creating height map:
+
+       Use GDAL (Geospatial Data Abstraction Library): Use command-line 
+       tools like gdal_translate or gdalwarp to extract the elevation data 
+       from the .tif and the unzipped LiDAR files.
+
+       Reproject to a Common Grid: Crop and reproject all of these datasets 
+       into a matching coordinate system (like UTM Zone 10N) and resample 
+       them onto a single, standardized 2D grid. Layer them so that the 
+       high-resolution LiDAR overrides the coarser USGS data where they overlap.
+
+       Generate a Height Map Texture: Convert this final 2D grid of 
+       elevation values into a single-channel floating-point data structure. 
+       In OpenGL, you will load this directly into VRAM as a GL_R32F 
+       (32-bit floating-point red channel) 2D texture, where the texture 
+       coordinates $(u, v)$ represent latitude/longitude or local grid 
+       coordinates, and the pixel value represents the height above sea level.
+
+       The texture will need to be moved around for the police boat ppi radar, but it
+       will be stationary for the vessel traffic control ppi radar.
+  
+
 ==================================
 
 End of discussion