[EPIC] Support for ColumnLayer (extruded point values)

[cboettig]

Context

I'd like to be able to use lonboard to create 3d mapping of data that include extruded column layers, like this (pure pydeck code below).

Issue

I'd like to be able to translate this pure-pydeck example into lonboard (i.e. as proof-of-principle for support for this layer).

import geopandas as gpd
import pydeck as pdk

DATA_URL = 'https://data.source.coop/cboettig/conservation-policy/Inflation_Reduction_Act_Projects.geojson'
df = gpd.read_file(DATA_URL)

column_layer = pdk.Layer(
    "ColumnLayer",
    data=df,
    get_position=["LONGITUDE", "LATITUDE"],
    get_elevation="FUNDING_NUMERIC",
    get_fill_color = [256,256,0, 140],
    elevation_scale=.01,
    radius=10000,
    pickable=True,
    auto_highlight=True,
)

INITIAL_VIEW_STATE = pdk.ViewState(latitude=35, longitude=-100, zoom=4, max_zoom=16, pitch=45, bearing=0)

r = pdk.Deck(
    column_layer,
    initial_view_state = INITIAL_VIEW_STATE,
    map_style=pdk.map_styles.CARTO_ROAD,
)
r

I think the key piece here is just adding support for "ColumnLayer", but not sure. Ideally I'd like to be able to layer this kind of rendering with other layers also generated in lonboard.

[kylebarron]

Indeed, the primary functionality that needs to be added is support for ColumnLayer. It should be relatively straightforward.

Though on the JS side there's a question of whether to add this functionality to https://github.com/geoarrow/deck.gl-layers now that there's a semi-official fork in https://github.com/visgl/deck.gl-community that I haven't had time to engage with yet.

[kylebarron]

Oh actually there's already a ColumnLayer in deck.gl-layers https://github.com/geoarrow/deck.gl-layers/blob/main/src/column-layer.ts. So we only need to touch the Lonboard side

[kylebarron]

In case you have an interest in making a PR, adding the ColumnLayer should be very similar to adding the PolygonLayer, so you should be able to use that PR as guidance. #330

It turns out that we already have the column layer on the JS side

lonboard/src/model/layer.ts

Line 264 in 5560ead

export class ColumnModel extends BaseArrowLayerModel {

so we only need to add the Python bits