City-Lifeline-Cockpit/.scratch/gis-investigation-subagent/findings.md

Local GIS Image Investigation

Input: two supplied image crops (regular 100x84, southern 200x175); source restricted to D:\GIS\GIS\yuanlingPic3 tiles plus D:\GIS\GIS\planet_110.059,28.258_110.744,28.625-shp\shpOutput.zip local road data. Bounds used: [110.328749941417,28.3917230659234,110.465779226663,28.4913038992907]. No application files changed or app server started.

Regular estate

• High confidence footprint match at approximately lon 110.40056, lat 28.44121; location tolerance about 50 m, not an entrance or parcel centroid claim.
• Reference and local zoom-19 image share three columns of staggered dark/red horizontal roofs, pale parallel internal lanes, a curved perimeter road on the east, bare reddish construction earth NW, and wooded land east. Nearby similarly colored development farther west has far more rows and is not the same footprint.
• Evidence: regular-z19.jpg is a 5x5 mosaic, z19 x422924..422928; top-to-bottom TMS y305380..305376. Its center pixel (640,640) is 110.40058136 E, 28.44122326 N. regular-in-south-best.jpg is the visually matching crop at image scale; regular-reference-upscaled.png enlarges the reference without smoothing. Local OSM residential access roads lie about 33 and 42 m from the estimated center (osm_id 1285336549 and 1285336551).
• An earlier western candidate around 110.3561,28.4590 is rejected: its estate has many more rows and a different footprint.

Southern apartment/development image

• Moderate-low confidence sector, not a proved point: candidate extent roughly lon 110.4028..110.4123, lat 28.4303..28.4377, provisional center lon 110.40756, lat 28.43401. The center is a search anchor only, and should not be used as a building coordinate.
• Broad landmarks in southern-same-size.jpg (200x175, matching reference dimensions): broad N-S road dividing west and east apartment groups, reddish cleared ground west and southwest, short transverse road, curved subdivision lanes NE, darker taller blocks SE. southern-z19.jpg supplies detailed source context. Local OSM S228/龙兴路 segments are approximately 54..66 m from provisional center.
• Important mismatch: roof colors/individual row spacing are not pixel-exact; approximate normalized gray image scores were only about 0.30, with other low-scoring false matches. The crop resolution and changes across imagery dates limit certainty. Do not report an exact apartment address or coordinate without a better reference image or distinctive extra landmark.
• The z18 tile containing provisional center is x211468, TMS y152683. The southern-z18.jpg montage covers x211458..211471 and top-to-bottom TMS y152692..152679.

Reproduction and coordinate math

tile-mosaic.ps1 stitches the locally stored files into north-up imagery; despite .png filenames, tile bytes are JPEG. For example from workspace root:

& '.\.scratch\gis-investigation-subagent\tile-mosaic.ps1' -Zoom 19 -Bounds 110.3993,28.4399,110.4018,28.4425 -MaxWidth 3000 -Output '.\.scratch\gis-investigation-subagent\regular-z19-repro.jpg'

The drawing loops increasing Google/slippy y downward and reads disk TMS y as 2^zoom - 1 - googleY; thus TMS rows DECREASE down the image. For mosaic pixel (px,py) with tileX0, googleY0, tile output size 256 px (no downscale): X=tileX0+px/256, Y=googleY0+py/256, lon=360*X/2^zoom-180, lat=atan(sinh(pi*(1-2*Y/2^zoom)))*180/pi. If output is downscaled, divide pixels by the actual displayed tile size instead of 256. For regular-z19.jpg, tileX0=422924, googleY0=218907, top disk TMS row=305380. Optional crop.cjs uses the installed Jimp package for visual crops; match-crops.cjs and coarse-search.cjs contain exploratory correlation scans, not proof of a southern point.