diff --git a/tasks/enduro-trails/scripts/tri_max_regen.sh b/tasks/enduro-trails/scripts/tri_max_regen.sh
new file mode 100644
index 0000000..ccb4568
--- /dev/null
+++ b/tasks/enduro-trails/scripts/tri_max_regen.sh
@@ -0,0 +1,125 @@
+#!/bin/bash
+set -e
+
+echo '=== TRI REGENERATION WITH MAX-AGGREGATION FOR LOW ZOOMS ==='
+echo "Start: $(date)"
+
+TMP='/tmp/tri_gen'
+SRTM_DIR='/home/slin/enduro-trails/data/srtm'
+TERRAIN_DIR='/home/slin/enduro-trails/data/terrain'
+TRI_DIR="${TERRAIN_DIR}/tri"
+
+mkdir -p $TMP
+
+echo ''
+echo '=== Step 1: Check tri_raw_full.tif ==='
+if [ -f "$TMP/tri_raw_full.tif" ]; then
+  echo "tri_raw_full.tif exists:"
+  gdalinfo -stats $TMP/tri_raw_full.tif 2>&1 | grep -E "Size|STATISTICS" || true
+else
+  echo "tri_raw_full.tif NOT FOUND — regenerating from SRTM..."
+  find $SRTM_DIR -name '*.hgt' > $TMP/hgt_list.txt
+  echo "HGT files: $(wc -l < $TMP/hgt_list.txt)"
+  gdalbuildvrt -vrtnodata -32768 -overwrite -input_file_list $TMP/hgt_list.txt $TMP/srtm.vrt
+  gdaldem TRI $TMP/srtm.vrt $TMP/tri_raw_full.tif -of GTiff -co COMPRESS=LZW -co BIGTIFF=YES -compute_edges
+  echo "TRI computed:"
+  gdalinfo -stats $TMP/tri_raw_full.tif 2>&1 | grep -E "Size|STATISTICS" || true
+fi
+
+echo ''
+echo '=== Step 2: Add overviews with MAX resampling ==='
+# Check GDAL version for -r max support
+GDAL_VER=$(gdal-config --version 2>/dev/null || gdalinfo --version | grep -oP '\d+\.\d+')
+echo "GDAL version: $GDAL_VER"
+
+# Try gdaladdo -r max
+if gdaladdo -r max --config COMPRESS_OVERVIEW LZW $TMP/tri_raw_full.tif 2 4 8 16 32 64 2>&1; then
+  echo "Overviews with MAX added successfully"
+  gdalinfo $TMP/tri_raw_full.tif 2>&1 | grep -i "overview" || true
+else
+  echo "gdaladdo -r max FAILED — using gdalwarp fallback"
+  # Fallback: create a low-res version with max resampling
+  gdalwarp -r max \
+    -tr 0.01 0.01 \
+    $TMP/tri_raw_full.tif \
+    $TMP/tri_raw_lowres.tif \
+    -co COMPRESS=LZW -overwrite
+  echo "Low-res TRI created:"
+  gdalinfo -stats $TMP/tri_raw_lowres.tif 2>&1 | grep -E "Size|STATISTICS" || true
+fi
+
+echo ''
+echo '=== Step 3: Color relief (v5 ramp, threshold 15) ==='
+cat > $TMP/tri_color_max.txt << 'RAMP'
+nv    0    0    0    0
+0     0    0    0    0
+14    0    0    0    0
+15    255  255  100  60
+20    255  230  50   100
+25    255  200  0    140
+30    255  150  0    180
+40    255  100  0    200
+50    230  50   0    220
+65    200  0    0    235
+80    180  0   50    245
+100   150  0   100   255
+RAMP
+
+gdaldem color-relief \
+  $TMP/tri_raw_full.tif \
+  $TMP/tri_color_max.txt \
+  $TMP/tri_colored_max.tif \
+  -alpha \
+  -of GTiff \
+  -co COMPRESS=LZW \
+  -co BIGTIFF=YES
+
+echo "Colored TRI created:"
+gdalinfo -stats $TMP/tri_colored_max.tif 2>&1 | grep STATISTICS_MAX || true
+
+echo ''
+echo '=== Step 3-alt: Add overviews to colored file (max on RGBA) ==='
+gdaladdo -r max --config COMPRESS_OVERVIEW LZW $TMP/tri_colored_max.tif 2 4 8 16 32 64 2>&1 || true
+echo "Overviews on colored file:"
+gdalinfo $TMP/tri_colored_max.tif 2>&1 | grep -i "overview" || true
+
+echo ''
+echo '=== Step 4: Generate tiles ==='
+rm -rf ${TRI_DIR}
+mkdir -p ${TRI_DIR}
+
+gdal2tiles.py \
+  --zoom=5-12 \
+  --processes=4 \
+  --tilesize=256 \
+  --resampling=average \
+  --webviewer=none \
+  $TMP/tri_colored_max.tif \
+  ${TRI_DIR}/
+
+echo ''
+echo '=== Step 5: Stats ==='
+for z in 5 6 7 8 9 10 11 12; do
+  total=$(find ${TRI_DIR}/$z/ -name '*.png' 2>/dev/null | wc -l)
+  nonempty=$(find ${TRI_DIR}/$z/ -name '*.png' -size +400c 2>/dev/null | wc -l)
+  echo "  zoom $z: $total total, $nonempty non-empty"
+done
+
+echo ''
+echo '=== Step 6: Sample tile check ==='
+TILE=$(find ${TRI_DIR}/7/ -name '*.png' -size +1000c 2>/dev/null | head -1)
+if [ -n "$TILE" ]; then
+  echo "Sample tile: $TILE"
+  python3 -c "from PIL import Image; im=Image.open('$TILE'); print('Size:', im.size, 'Mode:', im.mode, 'Extrema:', im.getextrema())" 2>/dev/null || file "$TILE"
+else
+  echo "No non-empty tiles found at zoom 7!"
+fi
+
+echo ''
+echo '=== Step 7: Average tile size at zoom 7 ==='
+find ${TRI_DIR}/7/ -name '*.png' -size +400c -exec ls -la {} \; 2>/dev/null | awk '{sum+=$5; n++} END {if(n>0) print "avg:", sum/n, "bytes, count:", n; else print "no tiles"}'
+
+echo ''
+du -sh ${TRI_DIR}
+echo '=== DONE ==='
+echo "End: $(date)"
diff --git a/tasks/enduro-trails/scripts/tri_max_regen_v2.sh b/tasks/enduro-trails/scripts/tri_max_regen_v2.sh
new file mode 100644
index 0000000..48d745d
--- /dev/null
+++ b/tasks/enduro-trails/scripts/tri_max_regen_v2.sh
@@ -0,0 +1,117 @@
+#!/bin/bash
+set -e
+
+echo '=== TRI MAX-AGGREGATION REGEN (GDAL 3.4 compatible) ==='
+echo "Start: $(date)"
+
+TMP='/tmp/tri_gen'
+TERRAIN_DIR='/home/slin/enduro-trails/data/terrain'
+TRI_DIR="${TERRAIN_DIR}/tri"
+
+mkdir -p $TMP
+
+echo ''
+echo '=== Step 1: Verify tri_raw_full.tif ==='
+if [ ! -f "$TMP/tri_raw_full.tif" ]; then
+  echo "FATAL: tri_raw_full.tif not found"
+  exit 1
+fi
+echo "OK: $(gdalinfo $TMP/tri_raw_full.tif 2>&1 | grep 'Size is')"
+
+echo ''
+echo '=== Step 2: Color relief (v5 ramp, threshold 15) ==='
+cat > $TMP/tri_color_max.txt << 'RAMP'
+nv    0    0    0    0
+0     0    0    0    0
+14    0    0    0    0
+15    255  255  100  60
+20    255  230  50   100
+25    255  200  0    140
+30    255  150  0    180
+40    255  100  0    200
+50    230  50   0    220
+65    200  0    0    235
+80    180  0   50    245
+100   150  0   100   255
+RAMP
+
+gdaldem color-relief \
+  $TMP/tri_raw_full.tif \
+  $TMP/tri_color_max.txt \
+  $TMP/tri_colored_max.tif \
+  -alpha \
+  -of GTiff \
+  -co COMPRESS=LZW \
+  -co BIGTIFF=YES
+echo "Colored TRI: $(du -sh $TMP/tri_colored_max.tif | cut -f1)"
+
+echo ''
+echo '=== Step 3: Create low-res version with MAX resampling ==='
+# Target resolution ~0.005 deg (~500m) for zooms 5-9
+# gdalwarp -r max works on GDAL 3.4 (unlike gdaladdo -r max)
+gdalwarp -r max \
+  -tr 0.005 0.005 \
+  -srcnodata "0 0 0 0" \
+  $TMP/tri_colored_max.tif \
+  $TMP/tri_colored_lowres.tif \
+  -co COMPRESS=LZW \
+  -co BIGTIFF=YES \
+  -overwrite
+echo "Low-res colored TRI: $(du -sh $TMP/tri_colored_lowres.tif | cut -f1)"
+echo "Size: $(gdalinfo $TMP/tri_colored_lowres.tif 2>&1 | grep 'Size is')"
+
+echo ''
+echo '=== Step 4: Clean output directory ==='
+rm -rf ${TRI_DIR}
+mkdir -p ${TRI_DIR}
+
+echo ''
+echo '=== Step 5: Generate tiles z5-9 from LOW-RES (max-aggregated) ==='
+gdal2tiles.py \
+  --zoom=5-9 \
+  --processes=4 \
+  --tilesize=256 \
+  --resampling=average \
+  --webviewer=none \
+  $TMP/tri_colored_lowres.tif \
+  ${TRI_DIR}/
+echo "Low zoom tiles done"
+
+echo ''
+echo '=== Step 6: Generate tiles z10-12 from FULL-RES ==='
+gdal2tiles.py \
+  --zoom=10-12 \
+  --processes=4 \
+  --tilesize=256 \
+  --resampling=average \
+  --webviewer=none \
+  $TMP/tri_colored_max.tif \
+  ${TRI_DIR}/
+echo "High zoom tiles done"
+
+echo ''
+echo '=== Step 7: Stats ==='
+for z in 5 6 7 8 9 10 11 12; do
+  total=$(find ${TRI_DIR}/$z/ -name '*.png' 2>/dev/null | wc -l)
+  nonempty=$(find ${TRI_DIR}/$z/ -name '*.png' -size +400c 2>/dev/null | wc -l)
+  echo "  zoom $z: $total total, $nonempty non-empty"
+done
+
+echo ''
+echo '=== Step 8: Sample tile check (zoom 7) ==='
+TILE=$(find ${TRI_DIR}/7/ -name '*.png' -size +1000c 2>/dev/null | head -1)
+if [ -n "$TILE" ]; then
+  echo "Sample: $TILE"
+  python3 -c "from PIL import Image; im=Image.open('$TILE'); print('Size:', im.size, 'Mode:', im.mode); bands=im.split(); print('R range:', bands[0].getextrema(), 'A range:', bands[3].getextrema())" 2>/dev/null || file "$TILE"
+else
+  echo "No large tiles at zoom 7"
+fi
+
+echo ''
+echo '=== Step 9: Avg tile size at zoom 7 ==='
+find ${TRI_DIR}/7/ -name '*.png' -size +400c -exec ls -la {} \; 2>/dev/null | awk '{sum+=$5; n++} END {if(n>0) print "avg:", sum/n, "bytes, count:", n; else print "no tiles"}'
+
+echo ''
+du -sh ${TRI_DIR}
+echo '=== DONE ==='
+echo "End: $(date)"