Fix projection for mercator requests (#27)

* Fix projection for mercator requests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

xpublish_wms/grid.py

@@ -7,7 +7,8 @@
 
 class GridType(Enum):
     REGULAR = 1
-    SGRID = 2
+    NON_DIMENSIONAL = 2
+    SGRID = 3
     UNSUPPORTED = 255
 
     @classmethod
@@ -16,7 +17,9 @@ def from_ds(cls, ds: xr.Dataset):
             return cls.SGRID
 
         try:
-            if "latitude" in ds.cf["latitude"].dims:
+            if len(ds.cf["latitude"].dims) > 1:
+                return cls.NON_DIMENSIONAL
+            elif "latitude" in ds.cf["latitude"].dims:
                 return cls.REGULAR
         except Exception:
             return cls.UNSUPPORTED

xpublish_wms/wms/get_map.py

@@ -6,16 +6,18 @@
 
 import cachey
 import cf_xarray  # noqa
+import dask.array as dask_array
 import datashader as dsh
 import datashader.transfer_functions as tf
 import matplotlib.cm as cm
 import numpy as np
 import pandas as pd
+import rioxarray  # noqa
 import xarray as xr
 from fastapi.responses import StreamingResponse
 
 from xpublish_wms.grid import GridType
-from xpublish_wms.utils import to_lnglat
+from xpublish_wms.utils import to_mercator
 
 logger = logging.getLogger("uvicorn")
 
@@ -255,30 +257,53 @@ def render_quad_grid(
     ) -> Union[bool, dict]:
         """
         Render the data array into an image buffer when the dataset is using a
-        regular or staggered (ala ROMS) grid
+        2d grid
         :param da:
         :return:
         """
-
+        projection_start = time.time()
         if self.crs == "EPSG:3857":
-            bbox_lng, bbox_lat = to_lnglat.transform(
-                [self.bbox[0], self.bbox[2]],
-                [self.bbox[1], self.bbox[3]],
-            )
-            bbox_ll = [*bbox_lng, *bbox_lat]
+            if (
+                self.grid_type == GridType.NON_DIMENSIONAL
+                or self.grid_type == GridType.SGRID
+            ):
+                x, y = to_mercator.transform(da.cf["longitude"], da.cf["latitude"])
+                x_chunks = (
+                    da.cf["longitude"].chunks if da.cf["longitude"].chunks else x.shape
+                )
+                y_chunks = (
+                    da.cf["latitude"].chunks if da.cf["latitude"].chunks else y.shape
+                )
+
+                da = da.assign_coords(
+                    {
+                        "x": (
+                            da.cf["longitude"].dims,
+                            dask_array.from_array(x, chunks=x_chunks),
+                        ),
+                        "y": (
+                            da.cf["latitude"].dims,
+                            dask_array.from_array(y, chunks=y_chunks),
+                        ),
+                    },
+                )
+            elif self.grid_type == GridType.REGULAR:
+                da = da.rio.reproject("EPSG:3857")
         else:
-            bbox_ll = [self.bbox[0], self.bbox[2], self.bbox[1], self.bbox[3]]
+            da = da.assign_coords({"x": da.cf["longitude"], "y": da.cf["latitude"]})
+
+        logger.debug(f"Projection time: {time.time() - projection_start}")
 
         if minmax_only:
             da = da.persist()
-            x = np.array(da.cf["longitude"].values)
-            y = np.array(da.cf["latitude"].values)
+            x = np.array(da.x.values)
+            y = np.array(da.y.values)
             data = np.array(da.values)
             inds = np.where(
-                (x >= (bbox_ll[0] - 0.18))
-                & (x <= (bbox_ll[1] + 0.18))
-                & (y >= (bbox_ll[2] - 0.18))
-                & (y <= (bbox_ll[3] + 0.18)),
+                (x >= (self.bbox[0] - 0.18))
+                & (x <= (self.bbox[2] + 0.18))
+                & (y >= (self.bbox[1] - 0.18))
+                & (y <= (self.bbox[3] + 0.18)),
             )
             # x_sel = x[inds].flatten()
             # y_sel = y[inds].flatten()
@@ -295,23 +320,23 @@ def render_quad_grid(
 
         start_dask = time.time()
         da.persist()
-        da.cf["latitude"].persist()
-        da.cf["longitude"].persist()
+        da.y.persist()
+        da.x.persist()
         logger.debug(f"dask compute: {time.time() - start_dask}")
 
         start_shade = time.time()
         cvs = dsh.Canvas(
             plot_height=self.height,
             plot_width=self.width,
-            x_range=(bbox_ll[0], bbox_ll[1]),
-            y_range=(bbox_ll[2], bbox_ll[3]),
+            x_range=(self.bbox[0], self.bbox[2]),
+            y_range=(self.bbox[1], self.bbox[3]),
         )
 
         shaded = tf.shade(
             cvs.quadmesh(
                 da,
-                x=da.cf.coords["longitude"].name,
-                y=da.cf.coords["latitude"].name,
+                x="x",
+                y="y",
             ),
             cmap=cm.get_cmap(self.palettename),
             how="linear",