🎯 ROI Extraction

The localtileserver.TileClient class has a few methods for extracting regions of interest (ROIs):

• localtileserver.TileClient.extract_roi()

• localtileserver.TileClient.extract_roi_shape()

• localtileserver.TileClient.extract_roi_pixel()

These methods can be used to extract rectangular regions from large images using world coordinates, Shapely geometry, or pixel bounds.

Note

The following example needs shapely to be installed.

from localtileserver import examples, get_leaflet_tile_layer
from ipyleaflet import Map, WKTLayer

client = examples.get_san_francisco()
presidio_roi = examples.load_presidio()

presidio_layer = WKTLayer(
  wkt_string=presidio_roi.wkt,
  style={'fillOpacity': 0, 'weight': 1},
  hover_style={
      'color': 'white', 'fillOpacity': 0
  },
)

m = Map(center=client.center(), zoom=client.default_zoom)
m.add_layer(get_leaflet_tile_layer(client))
m.add_layer(presidio_layer)
m

Perform ROI extraction with Shapely object

presidio = client.extract_roi_shape(presidio_roi, encoding='PNG', return_bytes=True)
presidio

---

from localtileserver import TileClient, get_leaflet_tile_layer, examples
from ipyleaflet import Map, WKTLayer

client = examples.get_san_francisco()
presidio_roi = examples.load_presidio()

# Perform ROI extraction with Shapely object
presidio = client.extract_roi_shape(presidio_roi)

presidio_layer = WKTLayer(
  wkt_string=presidio.wkt,
  style={'fillOpacity': 0, 'weight': 1},
  hover_style={
      'color': 'white', 'fillOpacity': 0
  },
)

m = Map(center=presidio.center(), zoom=presidio.default_zoom)
m.add_layer(get_leaflet_tile_layer(presidio))
m.add_layer(presidio_layer)
m

User Interface with ipyleaflet

I have included the get_leaflet_roi_controls() utility to create some leaflet UI controls for extracting regions of interest from a tile client. You can use it as follows and then draw a polygon and click the “Extract ROI” button.

The outputs are save in your working directory by default (next to the Jupyter notebook).

from localtileserver import get_leaflet_tile_layer, get_leaflet_roi_controls
from localtileserver import examples
from ipyleaflet import Map

# First, create a TileClient from example raster file
client = examples.get_san_francisco()

# Create ipyleaflet tile layer from that server
t = get_leaflet_tile_layer(client)

# Create ipyleaflet controls to extract an ROI
draw_control, roi_control = get_leaflet_roi_controls(client)

# Create ipyleaflet map, add layers, add controls, and display
m = Map(center=(37.7249511580583, -122.27230466902257), zoom=9)
m.add_layer(t)
m.add_control(draw_control)
m.add_control(roi_control)
m