Expected behavior and actual behavior.

I would like to extract connected shapes from an int64 array. Unfortunately, rasterio.features.shapes does not support int64 dtypes, but it claims to support float32 and float64. However, if I cast my array to either of those types, the returned label values are incorrect.

Steps to reproduce the problem.

import numpy as np
import rasterio.features

image_int64 = np.zeros((5, 5), dtype=np.int64)
label1 = np.iinfo(np.int32).max + 100
label2 = np.iinfo(np.int32).max + 1000

image_int64[:2, :2] = label1
image_int64[3:, 3:] = label2
print(image_int64)

polygons = list(rasterio.features.shapes(image_int64.astype(float)))
for polygon in polygons:
    print(polygon[1])

polygons = list(rasterio.features.shapes(image_int64.astype(np.float32)))
for polygon in polygons:
    print(polygon[1])

The output is:

[[2147483747 2147483747          0          0          0]
 [2147483747 2147483747          0          0          0]
 [         0          0          0          0          0]
 [         0          0          0 2147484647 2147484647]
 [         0          0          0 2147484647 2147484647]]

2147483648.0 0.0 2147484672.0
2147483648.0 0.0 2147484672.0

The returned labels do not match the values in the input image.

Is there any chance that support for np.int64 dtypes could be added to rasterio.features.shapes?

Environment Information

rasterio info:
rasterio: 1.4.3
GDAL: 3.9.3
PROJ: 9.4.1
GEOS: 0.0.0
PROJ DATA: /Users/lbradley/.venvs/photutils-dev/lib/python3.13/site-packages/rasterio/proj_data
GDAL DATA: /Users/lbradley/.venvs/photutils-dev/lib/python3.13/site-packages/rasterio/gdal_data

System:
python: 3.13.4 (main, Jun 5 2025, 13:09:21) [Clang 17.0.0 (clang-1700.0.13.5)]
executable: /Users/lbradley/.venvs/photutils-dev/bin/python
machine: macOS-15.5-arm64-arm-64bit-Mach-O

Python deps:
affine: 2.4.0
attrs: 25.3.0
certifi: 2025.06.15
click: 8.2.1
cligj: 0.7.2
cython: None
numpy: 2.3.1
click-plugins: None
setuptools: 80.9.0

Installation Method

Installed from PyPI using pip 25.1.1.