forked from
anil.recoil.org/monopam-myspace
My aggregated monorepo of OCaml code, automaintained
Fix UTM pixel mapping in reprojection — remove double row_start subtraction
utm_n is already offset by row_start, so subtracting row_start again
gave wrong pixel indices (all out of bounds → grey overlay).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
+4
-3
+4
-3
tessera-zarr/lib/tessera_zarr.ml
+4
-3
tessera-zarr/lib/tessera_zarr.ml
···
136
136
(Float.of_int oj +. 0.5) *. (wgs_bbox.max_lon -. wgs_bbox.min_lon)
137
137
/. Float.of_int out_w in
138
138
let (e, n) = Geotessera.Utm.wgs84_to_utm ~zone lon lat in
139
-
(* Map UTM coord to input pixel *)
140
-
let pi = Float.to_int (Float.floor ((utm_n -. n) /. pixel_size))
141
-
- row_start in
139
+
(* Map UTM coord to local pixel in mat.
140
+
Row 0 = utm_n (north edge), row increases southward.
141
+
Col 0 = utm_w (west edge), col increases eastward. *)
142
+
let pi = Float.to_int (Float.floor ((utm_n -. n) /. pixel_size)) in
142
143
let pj = Float.to_int (Float.floor ((e -. utm_w) /. pixel_size)) in
143
144
if pi >= 0 && pi < tile_h && pj >= 0 && pj < tile_w then begin
144
145
let in_idx = pi * tile_w + pj in