GIS

The VRT driver is a format driver for GDAL that allows a virtual GDAL dataset to be composed from other GDAL datasets with repositioning, and algorithms potentially applied as well as various kinds of metadata altered or added. VRT descriptions of datasets can be saved in an XML format normally given the extension .vrt.

gdalbuildvrt [--help] [--long-usage] [--help-general] [--quiet] [[-strict]|[-non_strict]] [-tile_index <field_name>] [-resolution user|average|common|highest|lowest|same] [-tr <xres> <yes>] [-input_file_list <filename>] [[-separate]|[-pixel-function <function>]] [-pixel-function-arg <NAME>=<VALUE>]... [-allow_projection_difference] [-sd <n>] [-tap] [-te <xmin> <ymin> <xmax> <ymax>] [-addalpha] [-b <band>]... [-hidenodata] [-overwrite] [-srcnodata "<value>[ <value>]..."] [-vrtnodata "<value>[ <value>]..."] [-a_srs <srs_def>] [-r nearest|bilinear|cubic|cubicspline|lanczos|average|mode] [-oo <NAME>=<VALUE>]... [-co <NAME>=<VALUE>]... [-ignore_srcmaskband] [-nodata_max_mask_threshold <threshold>] <vrt_dataset_name> [<src_dataset_name>]...

This program builds a VRT (Virtual Dataset) that is a mosaic of a list of input GDAL datasets. The list of input GDAL datasets can be specified at the end of the command line, put in a text file (one filename per line) for very long lists, or it can be a MapServer tileindex (see the gdaltindex utility). If using a tile index, all entries in the tile index will be added to the VRT.

Emphasizing clarity, accuracy, and purpose-driven design, the guide covers how to create compelling static and interactive visualizations tailored to diverse analytical and communicative objectives. Throughout, we will adhere to best practices in cartographic design to ensure that each visualization conveys its intended message clearly and truthfully.

Successful geospatial visualization demands attention to several core principles that ensure the resulting map or graphic is both informative and comprehensible. Visualizations must balance aesthetic considerations with functional accuracy to effectively convey spatial information.

Clarity and Simplicity Clarity in geospatial visualization means the core message of a map is immediately apparent to viewers. Overloading a map with too much information or too many design elements can confuse rather than enlighten. Designers should strive for minimalism—include only the critical spatial features and data relevant to the map’s purpose. An expert data visualization principle is to “remove any elements that do not contribute to understanding the data”, such as excessive labels, grid lines, or decorative clutter. By simplifying the visual display, we direct the audience’s attention to the most important patterns or locations. Key guidelines for simplicity include: Limit the number of thematic layers shown on a single map. Use intuitive symbols and clear labeling for features. Avoid excessive annotation or unnecessary visual noise. In practice, a clean design with ample white space and straightforward symbology will enhance comprehension and engagement. The goal is a map that communicates rather than overwhelms.

Appropriate Color Schemes: Choose color palettes that are perceptually uniform and appropriate for the data. Avoid using arbitrary or excessively bright colors that could mislead or cause eye strain. Instead, use scientifically derived colormaps like viridis or plasma, which are designed to be uniform and colorblind-friendly. For example, a sequential palette (light to dark in one hue) makes sense for a unipolar data range (e.g., population density), whereas a diverging palette (two hues fading to a neutral midpoint) is best for data that have a meaningful center (e.g., above/below average comparisons). Ensure that the colors have sufficient contrast against each other and the map background for readability – legend text and boundary lines should also be clearly visible. (A poorly chosen palette or low-contrast colors can render a map useless to colorblind viewers or even to those in print vs. screen viewing.) Maintain consistency in color use across multiple maps; if one map shows intensity of something in red, another map in the report should ideally use red for that same intensity concept.

Clear Legends and Annotations: Provide explanatory legends, titles, and annotations to guide the viewer. A well-crafted legend is crucial for interpreting a map’s symbology – it should be clear, concise, and not overly cluttered. Viewers should not struggle to match colors or symbols to their meaning. As a cartography guide points out, a confusing legend can undermine your visualization, whereas a clear legend “guides [readers] seamlessly through your data story”. Tips include: place the legend in an unobtrusive but noticeable location (often corners work well), use intuitive labels (e.g., “Population (millions)” rather than “Pop_val”), and avoid too many categories. Additionally, titles and subtitles are important: they frame what the map is about. A good title might state the what/where/when (e.g., “Population Distribution by Region, 2020”) so the audience immediately knows the context. Annotations like callout labels or arrows can highlight key insights (e.g., “Area X has the highest value”). However, avoid excessive text on the map itself; maintain a balance so the map doesn’t become a textbook diagram unless that’s intended. The goal is to inform without overwhelming.

1. Sequential schemes are suited to ordered data that progress from low to high. Lightness steps dominate the look of these schemes, with light colors for low data values to dark colors for high data values.

X TYPES OF COLOR SCHEMES 1. Sequential schemes are suited to ordered data that progress from low to high. Lightness steps dominate the look of these schemes, with light colors for low data values to dark colors for high data values. 2. Diverging schemes put equal emphasis on mid-range critical values and extremes at both ends of the data range. The critical class or break in the middle of the legend is emphasized with light colors and low and high extremes are emphasized with dark colors that have contrasting hues.

3. Qualitative schemes do not imply magnitude differences between legend classes, and hues are used to create the primary visual differences between classes. Qualitative schemes are best suited to representing nominal or categorical data.

The appearance and robustness of a color scheme is in part a product of what else goes on the map and the background over which you are trying to show your colors. Small differences in the color of linework or the presence of other map items (like labels) really has a big impact on the appearance of a color scheme, so be sure to try these options here before settling on a final color scheme. Overlay cities and roads for a first look at how well text and symbols can be read with the area colors you select. Though the examples we have chosen are highways and cities, they should give you a good idea of how other linework or typography will function on the map. We have also provided a grayscale DEM so you can see what happens to your colors when you combine them with other underlying map data: Generally speaking, colors become harder to distinguish and you will need to user fewer classes of data.

TIP: Try turning off the county borders or making them white; notice a big difference? Try changing the background surrounding the map to see how colors are changed by their surroundings.

Choosing the number of data classes is an important part of map design. Increasing the number of data classes will result in a more "information rich" map by decreasing the amount of data generalization. However, too many data classes may overwhelm the map reader with information and distract them from seeing general trends in the distribution. In addition, a large numbers of classes may compromise map legibility—more classes require more colors that become increasingly difficult to tell apart. Many cartographers advise that you use five to seven classes for a choropleth map. Isoline maps, or choropleth maps with very regular spatial patterns, can safely use more data classes because similar colors are seen next to each other, making them easier to distinguish.

Cloud-Optimized GeoTIFFs (COGs) are a specialized format of GeoTIFF designed to enable efficient access to raster data, particularly in cloud environments. By organizing data into tiled structures and enabling partial reads, COGs allow users to fetch only the portions they need, significantly reducing bandwidth and storage costs

The Modern Geospatial Data Stack: Trends, Tools, and What They Mean for You

In this post, I’ll break down the key trends shaping the modern geospatial data stack, highlight the tools and platforms that are leading innovation, and explain what this means for practitioners, teams, and organizations.

File Formats and Catalogs: The Foundation of Cloud-Native Geospatial

Modern analytics workflows are no longer small, local projects—they’re massive, distributed, and data-heavy. That’s why cloud-native file formats and data catalogs are at the center of the stack.

Apache Iceberg and other table formats are becoming the backbone of large-scale geospatial data management.

Cloud-optimized formats (like GeoParquet and COGs) make spatial data portable, efficient, and accessible.

Specialized systems like Earthmover are also adding focus for specific file types, in this case climate data

What this means for you: If you’re still relying on ad hoc file storage, you’re missing out on performance and scalability. Learning how to use catalogs like Iceberg lets you fully leverage file-level optimizations, versioning, and schema evolution—critical for handling large and evolving geospatial datasets.

Data Processing: Beyond the Spatial Join

For years, the hallmark of a spatial database was the ability to run a point-in-polygon query. But in 2025, that capability has been commoditized. Most OLAP systems and modern databases can handle these joins at scale—even without compute layers optimized for geospatial.

The real differentiator now is advanced geospatial processing: Zonal statistics for climate and land-use analysis Mobility data pipelines for transportation and urban planning Feature engineering for AI and machine learning workflows

Platforms like Wherobots and Coiled are focusing directly on these workloads, while Apache Spark has begun supporting vector data types. Traditional relational databases still play a role—especially as AI applications demand fast transactional access—but the future belongs to systems that optimize for large analytical queries across massive datasets.

👉 What this means for you: Stop thinking of “point-in-polygon” as the benchmark. Systems that can go deeper—into advanced feature generation and distributed geospatial computation—will define the next generation of spatial analytics.

Transformation and Orchestration: Moving Beyond Simple Scripts

In the past, geospatial data pipelines often relied on one-off Python scripts. Today, that approach simply doesn’t scale.

Specialized spatial ELT tools like Seer AI and BigGeo are emerging to handle geospatial-specific transformations.

Orchestration platforms such as Apache Airflow and Astronomer are essential for managing dependencies, scheduling, and ensuring upstream data integrity.

👉 What this means for you: Don’t think of orchestration as overhead—it’s how you guarantee reliable and reproducible data pipelines. If your team is serious about analytics, orchestration is no longer optional.

Analytical Tools: From Niche to End-to-End

The analytics ecosystem for geospatial continues to expand, giving users more choice than ever. Specialized platforms: Foursquare, Dekart, Superset, Preset End-to-end systems: CARTO and Fused, which combine geospatial with AI, data management, and visualization 👉 What this means for you: The decision is no longer “which GIS platform do I use?” Instead, it’s about picking the right tool for the specific stage of your workflow—sometimes a lightweight visualizer, sometimes a comprehensive enterprise solution.

GIS: The Rise of Web-Native Platforms Web GIS is where most of the visible innovation is happening. Platforms like Felt and Atlas are reimagining the GIS experience: collaborative, browser-based, and designed for simplicity without losing power. 👉 What this means for you: Expect the center of gravity in GIS to continue shifting from desktop to the web. Professionals who adapt to these tools will be better positioned for collaborative, cloud-based work environments.

AI: A New Category of Geospatial Tools One of the most exciting areas is the emergence of AI-native geospatial platforms. These tools are building with machine learning and agentic AI in mind from the start. Vertical-focused AI: Aino (planning), Contour (cities) GIS-focused AI: Bunting Labs, optimizing traditional GIS workloads with AI Agentic AI for geospatial: Klarety and Monarcha, building agents as spatial tools 👉 What this means for you: AI isn’t just an add-on anymore—it’s a defining capability. Expect to see AI-powered agents and models become critical in workflows from automated labeling to decision support.

Python Ecosystem: Expanding AI and Spatial ML Python remains the glue of modern geospatial, and the ecosystem keeps growing: TorchGeo has matured into an independent framework for spatial deep learning. GeoAI from Dr. Qiusheng Wu provides new capabilities for applying ML to spatial data. 👉 What this means for you: If you’re serious about geospatial and AI, Python is unavoidable. The tools are expanding, and open-source continues to lead the way.

Final Takeaway: Where the Modern Geospatial Stack is Headed The geospatial data stack is no longer about static maps or one-off analyses. It’s about: Scalable architectures (Iceberg, GeoParquet, COGs) Advanced processing (beyond spatial joins) Reliable pipelines (orchestration + transformation) AI-native design (feature engineering, agents, ML-ready workflows) The modern stack is maturing into a foundation for spatial intelligence at scale. If you’re a GIS professional, data engineer, or analyst, now is the time to expand your toolkit—because the organizations that master this new stack will define the future of geospatial.