Matthew Love¹², Christopher Amante¹², Elliot Lim¹², Michael MacFerrin¹², Matthew Fisher (mentor), Kelly Carignan (retired)

CUDEM Framework

The CUDEM framework provides a set of powerful open-source command-line tools as well as a Python-3-based application programming interface (API) for:

• Fetching: Identifying and downloading topographic and bathymetric source data from more than forty different publicly available datasets (e.g., NOAA, USGS, USACE).
• Processing: Filtering, cleaning, and masking source data (point clouds, rasters, vectors) to remove artifacts and enforce quality standards.
• Gridding: Ranking and merging multiple datasets using a variety of interpolation algorithms to generate seamless Digital Elevation Models (DEMs).
• Analysis: Generating auxiliary data products including uncertainty grids, data masks, and spatial metadata.
• Transformation: converting data between various horizontal and vertical datums.

Individual components are modular and may be run standalone; for example, the fetches module can download airborne lidar data or nautical charts covering specific geographic regions; the waffles module can generate DEMs from scattered data; and the grits module can filter and post-process those DEMs. The CUDEM tools may also be conjoined in end-to-end workflows ensuring permanent traceability and reproducibility in DEM generation.

Installation and Setup

Requirements

• Python 3.8+
• GDAL (and Python bindings) is required.
• Numpy, Scipy

Note on GDAL: GDAL can be difficult to install via pip alone due to compilation requirements. It is strongly recommended that users install GDAL via their system package manager (e.g., apt install python3-gdal) or Conda (conda install gdal) before pip installing cudem.

Other useful external programs needed for full functionality include:

• GMT / PyGMT: For gridding and filtering options.
• MB-System: For processing raw bathymetric sonar formats.
• VDatum: For vertical datum transformations.

Install via Pip

Download and install git (If you have not already): git installation

pip install git+https://github.com/ciresdem/cudem.git#egg=cudem

Install via Conda

It is recommended to use a conda environment to manage GDAL and other geospatial dependencies.

conda create -n cudem -c conda-forge gdal gmt pygmt numpy scipy pandas pyproj utm requests lxml matplotlib laspy h5py boto3 tqdm mercantile git netCDF4 h5netcdf libgdal-hdf5 libgdal-netcdf pyhdf pip scikit-image
conda activate cudem
pip install laspy[laszip]
pip install --upgrade --no-deps git+[https://github.com/ciresdem/cudem.git](https://github.com/ciresdem/cudem.git)

Extras

• Windows: Install windows-curses via pip: pip install windows-curses
• MB-System: Installation Instructions
• HTDP / VDatum: See NOAA Geodesy Tools.

Modules

The CUDEM suite is composed of several key modules, each accessible via command-line tools or Python API:

CUDEM Modules

Module	Description	CLI Command
fetches	Data Acquisition: Fetch elevation data from a wide variety of public online sources (NOAA, USGS, USACE, etc.).	fetches
pointz	Point-Cloud Filtering: A powerful filtering engine to filter Point Clouds.	pointz
grits	Grid Filtering & Post-Processing: A powerful filtering engine to smooth, clean, blend, and analyze raster DEMs.	grits
dlim	Data Lists & Processing: Process, clean, and standardize diverse data types (XYZ, Raster, LAS, COPC, etc.) into unified formats.	dlim
waffles	Gridding & interpolation: Generate Digital Elevation Models (DEMs) from scattered data using various algorithms (IDW, Spline, GMT Surface, etc.).	waffles
regions	Spatial Management: Process and manipulate bounding box regions and vector polygons.	regions
vdatums	Vertical Transformation: Generate vertical transformation grids and manage datums.	vdatums
perspecto	Visualization: Generate perspective images, hillshades, and color-relief maps of DEMs.	perspecto

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Module Summaries:

Fetches (Data Acquisition)

The fetches module automates the discovery and retrieval of geospatial data. It interfaces with over forty public APIs and repositories to download topographic and bathymetric data.

• Access data from federal agencies including NOAA (NOS, NCEI, OCM), USGS (3DEP, CoNED), USACE, and more.
• Download data specific to a bounding box or vector polygon.
• Seamlessly pipes downloaded data into processing workflows.

Dlim (Data Lists & Processing)

The dlim module serves as the primary data ingestion engine. It utilizes "datalists" (text-based configuration files) to manage, process, and standardize diverse datasets into a unified stream for gridding.

• Handles mixed formats (Raster, XYZ, LAS/LAZ, COPC) seamlessly, abstracting file-specific parsing.
• Supports on-the-fly vertical datum transformation, spatial clipping, and masking.
• Supports nested datalists for organized, multi-scale data management.

Pointz (Point Cloud Filtering)

The pointz module provides specialized tools for filtering and manipulating raw point cloud data (XYZ, LAS/LAZ) prior to gridding.

• Outlier Removal: Statistical filters (outlierz) to remove noise spikes and gross errors.
• Quality Control: Reference-based checks (rq) to validate data against known baselines.
• Masking: Filter points using vector polygons (vector_mask) or raster masks.
• Thinning: Reduce data density (block_minmax, density) for efficient processing.

Grits (Grid Filters)

The grits module provides a standardized framework for raster manipulation. It supports chunked processing for large files and can chain multiple filters together.

• Smoothing: blur (Gaussian), denoise (Median/Bilateral), gmtfilter (GMT wrapper).
• Cleaning: outliers (Statistical outlier removal), zscore (Local anomaly detection), flats (Remove artifacts).
• Restoration: fill (Void filling/inpainting via IDW or Spline), morphology (Erosion/Dilation).
• Integration: blend (Seamless blending of datasets), weights (Quality-based buffering), diff (Change detection).
• Hydrology: hydro (Sink filling).
• Geometry: cut (Mask to region), clip (Clip to vector), slope (Slope-based filtering).

Waffles (Gridding & Interpolation)

The waffles module serves as the primary DEM generation engine within the framework. It provides a unified factory interface to transform scattered elevation data into seamless raster surfaces using a wide range of gridding algorithms. It manages the entire production pipeline, from data ingestion and spatial partitioning (chunking) to interpolation and post-processing.

• Users can switch between different interpolation methods simply by changing the module flag (e.g., -M gmt-surface for spline, -M IDW for inverse distance weighting).

• Algorithms:

  • Internal: IDW (Inverse Distance Weighting), stacks (Weighted Mean/Supercedure), linear/cubic/nearest (Scipy-based), natural-neighbor (Sibson), kriging (Geostatistical), and ml-rf/ml-knn/ml-mlp (Machine Learning Regression (SciKit-based)).
  • Wrappers: surface / triangulate (GMT), mbgrid (MB-System), and gdal (GDAL Grid).
  • Specialized: coastline (Land/Water masking), vdatum (Vertical datum grids), inpaint (Void filling), and uncertainty (Interpolation error estimation).

• Supports "chunking" (-K) to process massive datasets by splitting the region into tiles, processing them in parallel, and merging the results.

• Pre-processes overlapping datasets into a weighted intermediate raster ("stack") to resolve conflicts before interpolation.

• Automatically handles buffering (-X) to prevent edge artifacts, clipping (-C) to vector polygons, and generating auxiliary products like uncertainty grids (-u) and data masks (-m).

Usage Examples

General

• Generate a CRM of Point Mugu in California
• Generate a set of Tiled CRMs of Northern California
• Generate a set of Tiled CUDEMs of North-West Washington State

Specific cli tools

• Fetching Data: fetches -R -90/-89/29/30 CUDEM
• Processing Data: dlim input.datalist -R -90/-89/29/30 -E .3s
• Generating DEM: waffles -M gmt-surface:tension=.35 -R -90/-89/29/30 -E .1s -O my_dem.tif input.xyz
• Filtering DEM: grits my_dem.tif -M outliers:k=2.5 -M fill:method=spline -M clip:src_ply=coast.shp -O clean_dem.tif
• Estimating Uncertainty: Docs

Additional Information

The CUDEM code repository is frequently updated, and code syntax is subject to change. Please see the code help function (--help) for the latest code syntax and examples. See Eakins and Grothe (2014) for more information on the challenges of building integrated DEMs and Eakins et al. (2015) for the initial specifications of the comprehensive DEM development framework. See Hare et al. (2011), Amante and Eakins (2016), and Amante (2018) for additional information on the DEM uncertainty.

For additional questions, please contact:

Matthew.Love@colorado.edu

Christopher.Amante@colorado.edu

Or ask questions, report bugs or make comments:

Project Board.

Zulip Channel.

Background

The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI), through its collaboration with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, develops digital elevation models (DEMs) that range from the local to global scale. Collectively, these elevation models are essential to determining the timing and extent of coastal inundation and improving community preparedness, event forecasting, and warning systems. We initiated a comprehensive framework at NCEI, the Continuously-Updated DEM (CUDEM) Program, to systematically generate DEMs from the local coastal community to the global scale.

We generate the CUDEMs through a standardized process using free and open-source software (FOSS) and provide open-access to our code repository (https://github.com/ciresdem) for consistency, transparency, and to promote accessibility. The CUDEM framework consists of systematic tiled geographic extents, spatial resolutions, and horizontal and vertical datums to facilitate rapid updates of targeted areas with new data collections, especially post-storm and tsunami events. The CUDEM Program is also enabling the rapid incorporation of high-resolution data collections ingested into local-scale DEMs into NOAA NCEI's suite of regional and global DEMs. The CUDEMs are a shift from project-based DEM specifications, to a comprehensive program that systematically and continuously develops and updates DEMs across all spatial scales.

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Code Citation

Love, M., Amante, C., Carignan, K., MacFerrin, M., & Lim, E. (2025). CUDEM (Version 3.0.1)

. [https://github.com/ciresdem/cudem]{.ul}

References

Amante CJ, Love M, Carignan K, Sutherland MG, MacFerrin M, Lim E. Continuously Updated Digital Elevation Models (CUDEMs) to Support Coastal Inundation Modeling. Remote Sensing. 2023; 15(6):1702. https://doi.org/10.3390/rs15061702

Amante, C. J. (2018). Estimating coastal digital elevation model uncertainty. Journal of Coastal Research, 34(6), 1382-1397. https://doi.org/10.2112/JCOASTRES-D-17-00211.1

Amante, C. J., & Eakins, B. W. (2016). Accuracy of interpolated bathymetry in digital elevation models. Journal of Coastal Research, (76 (10076)), 123-133. https://doi.org/10.2112/SI76-011

Eakins, B. W., & Grothe, P. R. (2014). Challenges in building coastal digital elevation models. Journal of Coastal Research, 30(5), 942-953.

Eakins, B. W., Danielson, J. J., Sutherland, M. G., & Mclean, S. J. (2015). A framework for a seamless depiction of merged bathymetry and topography along US coasts. In Proc. US Hydro. Conf (pp. 16-19).

Hare, R., Eakins, B., & Amante, C. J. (2011). Modelling bathymetric uncertainty. The International Hydrographic Review.

Footnotes

1. Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder ↩ ↩² ↩³ ↩⁴

2. National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) ↩ ↩² ↩³ ↩⁴