Explore all of the layers available from NASA EarthData GIBS.
Try the app here:
https://ahuang11.github.io/nasa-earth-data-gibs-wms-explorer/
Read the walkthrough here.
5 Likes
By the way, Iād also be interested to see how to rewrite this using param.Parametrized.
Right now, all the params/widgets are initialized in __init__; I think I did it this way because with param, I keep forgetting how to cast widgets and also update the second select options based on selections from the first input.
import panel as pn
import pandas as pd
import holoviews as hv
from owslib.wms import WebMapService
hv.extension("bokeh")
pn.extension(sizing_mode="stretch_width")
BASE_URL = "https://gibs.earthdata.nasa.gov/wms/epsg3857/best/wms.cgi?SERVICE=WMS"
XMIN = -20037507.539400
YMIN = 1638517.444800
XMAX = 20037260.918700
YMAX = 7714669.39460
class NasaEarthDataGibsWmsExplorer:
def __init__(self):
self.wms = WebMapService(BASE_URL)
layers = sorted(self.wms.contents)
self.products_layers = {"Miscellaneous": []}
for layer in layers:
if "_" in layer:
product, product_layer = layer.split("_", 1)
if product not in self.products_layers:
self.products_layers[product] = []
self.products_layers[product].append(product_layer)
else:
self.products_layers["Miscellaneous"].append(layer)
# create widgets
self.product_select = pn.widgets.Select(
name="Product",
options=sorted(self.products_layers),
)
self.layer_select = pn.widgets.Select(
name="Layer",
options=sorted(self.products_layers[self.product_select.value]),
)
self.time_slider = pn.widgets.DiscreteSlider(name="Time", margin=(5, 16))
self.refresh_button = pn.widgets.Button(name="Refresh", button_type="light")
self.image_pane = pn.pane.Image() # for colorbar / legend
self.holoviews_pane = pn.pane.HoloViews(min_height=500, sizing_mode="stretch_both")
pn.state.onload(self._onload)
def _onload(self):
# add interactivity
self.product_select.param.watch(self.update_layers, "value")
self.layer_select.param.watch(self.update_time, "value")
self.refresh_button.on_click(self.update_web_map)
# create imagery
base_map = hv.element.tiles.EsriImagery().opts(
xlim=(XMIN, XMAX), ylim=(YMIN, YMAX), responsive=True
)
self.dynamic_map = hv.DynamicMap(
self.update_web_map, streams=[self.time_slider.param.value_throttled]
)
self.holoviews_pane.object = base_map * self.dynamic_map
def get_layer(self, product=None, product_layer=None):
product = product or self.product_select.value
if product == "Miscellaneous":
layer = product_layer or self.layer_select.value
else:
layer = f"{product}_{product_layer or self.layer_select.value}"
return layer
def update_layers(self, event):
product = event.new
product_layers = self.products_layers[product]
self.layer_select.options = sorted(product_layers)
def update_time(self, event):
layer = self.get_layer()
time_positions = self.wms.contents[layer].timepositions
if time_positions:
ini, end, step = time_positions[0].split("/")
try:
freq = pd.Timedelta(step)
except ValueError:
freq = step.lstrip("P")
options = (
pd.date_range(ini, end, freq=freq)
.strftime("%Y-%m-%dT%H:%M:%SZ")
.tolist()
)
if options:
value = options[0]
self.time_slider.param.set_param(options=options, value=value)
return
# use N/A instead of None to circumvent Panel from crashing
# when going from time-dependent layer to time-independent layer
options = ["N/A"]
self.time_slider.options = options
self.time_slider.param.trigger("value_throttled")
def get_url_template(self, layer, time=None):
get_map_kwargs = dict(
layers=[layer],
srs="EPSG:3857",
bbox=(XMIN, YMIN, XMAX, YMAX),
size=(256, 256),
format="image/png",
transparent=True,
time=time
)
try:
url = self.wms.getmap(**get_map_kwargs).geturl()
except Exception:
get_map_kwargs.pop("time")
url = self.wms.getmap(**get_map_kwargs).geturl()
url_template = (
url.replace(str(XMIN), "{XMIN}")
.replace(str(YMIN), "{YMIN}")
.replace(str(XMAX), "{XMAX}")
.replace(str(YMAX), "{YMAX}")
)
return url_template
def update_web_map(self, value_throttled=None):
try:
self.holoviews_pane.loading = True
layer = self.get_layer()
time = self.time_slider.value
if time == "N/A":
time = None
url_template = self.get_url_template(layer, time)
layer_meta = self.wms[layer]
self.image_pane.object = layer_meta.styles.get("default", {}).get("legend")
layer_imagery = hv.Tiles(url_template).opts(title=layer_meta.title)
finally:
self.holoviews_pane.loading = False
return layer_imagery
def view(self):
widget_box = pn.WidgetBox(
self.product_select,
self.layer_select,
self.time_slider,
self.image_pane,
self.refresh_button,
pn.Spacer(sizing_mode="stretch_height"),
sizing_mode="stretch_both",
max_width=300,
)
return pn.Row(
widget_box,
self.holoviews_pane,
)
explorer = NasaEarthDataGibsWmsExplorer()
explorer.view().servable()
3 Likes
This is dope!
2 Likes
I concur really enjoyed this and the walk through material too
2 Likes