Question about rastering the osm

[SiYLin]

Thx for producing such great work!
I have met some questions about render raster mask function for osm data. During the render_raster_mask function, I find out multipoints(more than 10) in xy space are ploted as two or zero points after the cv2.polylines function.

[sarlinpe]

Thank you for reporting an issue, can you please provide a minimal code example that reproduces this?

[SiYLin]

Thanks for your helping! I have found out the real problem is that when we query elements from the bounding box. It gerneates lines/points outisde of the boundingbox. Here is the minimal code to reproduce the error. (All hard code numbers and parameters are from avigon.osm and related json)

from ..utils.geo import BoundaryBox, Projection
from .data import MapData
from .download import get_osm
from .parser import Groups
from .raster import Canvas, render_raster_map, render_raster_masks
from .reader import OSMData, OSMNode, OSMWay

osm = OSMData.from_file('./avigon.osm')
osm.add_xy_to_nodes(projection)
map_data = MapData.from_osm(osm)
map_index = MapIndex(map_data)
bbox_tile = ([-1507.6801249806967,-1083.4590254879367],[-1379.6801249806967,-955.4590254879367])
canvas = Canvas(bbox_tile, ppm)
nodes, lines, areas = map_index.query(bbox_tile)
print(lines)

It will get something like [-1395.64272195, -1090.34845149],
[-1483.56526137, -1128.99600827],
[-1576.82026528, -1169.08557396],
[-1610.25588428, -1184.96641715],
[-1656.72452035, -1209.31050901],
[-1683.04645824, -1223.09275943],
[-1718.85196607, -1242.26133847],
[-1741.42436825, -1254.84432836],
[-1764.96035421, -1267.54920678],
[-1801.02338149, -1287.15060517],
[-1824.35964077, -1302.64421344],
[-1837.21680909, -1312.9739888 ],
[-1850.76548401, -1326.80354365],
[-1865.88090246, -1344.32151594],
[-1877.82520615, -1362.75146288],
[-1888.57344251, -1381.84839481],
[-1897.28212891, -1400.12367128],
[-1904.56191997, -1419.19934585],
[-1911.04745617, -1440.29746137],
[-1913.45076729, -1449.35231573],
[-1919.67292496, -1475.71715968],
[-1923.53499303, -1503.58268054],
[-1924.87191517, -1517.63783432]])

[sarlinpe]

This is working as intended. The map index uses an R-tree to efficiently retrieve elements based on their bounding box:

OrienterNet/maploc/osm/tiling.py

Line 25 in 71e89eb

self.index_nodes = rtree.index.Index()

It returns any lines and polygons whose bounding box intersect with the query. OpenCV drawing functions support elements that are partially outside the canvas:

OrienterNet/maploc/osm/raster.py

Lines 45 to 53 in 71e89eb

	def draw_multipolygon(self, xys: List[np.ndarray]):
	uvs = [self.to_uv(xy).round().astype(np.int32) for xy in xys]
	cv2.fillPoly(self.raster, uvs, 255)
	def draw_line(self, xy: np.ndarray, width: float = 1):
	uv = self.to_uv(xy)
	cv2.polylines(
	self.raster, uv[None].round().astype(np.int32), False, 255, thickness=width
	)