When you are planning a GIS mapping project, ground resolution and scale are key considerations. Different resolutions are more or less appropriate for different scenarios. How do you choose the right resolution for your project?
At a glance:
- Ground resolution is a key consideration when creating a GIS map
- Different kinds of project benefit from different levels of spatial resolution
- We define key terms for GIS maps
- Get tips and insights on which scale and image resolution you need
Imagine you are sitting in the window seat of an airplane as it makes its descent to the ground. To start with, you can only see the big features of the landscape – the gray outline of cities, patches of forest, and farmland. But as the plane gets closer to the ground, individual roads come into view, then buildings, and, finally, individual vehicles, trees, and even people.
Anyone who’s observed this increasing detail at the end of a flight will intuitively understand the importance of ground resolution in GIS mapping. High-ground resolution gives you lots of detail close-up, but you can’t see the bigger picture. Low ground resolution lets you observe a wider area, but you see less detail.
Now, if you’re creating maps for a project, it’s not always clear which scale you need, and how much detail is required. Is a low-resolution image at the landscape scale sufficient, or do you need high-resolution images showing individual trees and buildings?
To decide what ground resolution you need in your GIS maps, it’s first useful to understand some key terms. We’ll then provide tips for which scale you need for different kinds of projects.
GIS key terms
Modern Geographic Information Systems (GIS) allow you to attach information to a map and identify trends, monitor change, and spot problems. If you want to create a GIS map, it’s important to understand key terms around scale and resolution.
- Ground resolution: In GIS, ground resolution (also known as spatial resolution) refers to the ground area represented in a single pixel on your computer screen. For example, if your GIS map has a 1 meter ground resolution, this means that each pixel would cover an area of 1 square meter.
- Scale: The scale of a map tells you how features depicted on it relate to the things they represent in the real world. A building on a map might be shown as 1 cm long, but in the real world it might be 10m in length. The map’s scale (1:1000 in this case) helps you understand the distances shown on the map.
- Ground sampling distance: GSD refers to the distance between the centers of two concurrent pixels on the ground. A low GSD of, say, 10 cm, means each pixel represents 10 cm on the ground. A higher GSD of 100 cm means each pixel represents one meter on the ground.
Different kinds of sensors can produce different GSD. The lowest GSD can be achieved using a drone to capture extremely high image resolution, whereas satellites capture higher GSD (but also cover a large area).
Factors to consider when choosing ground resolution for your maps
Different kinds of GIS projects will benefit from using imagery and maps of different scales and spatial resolutions. Here are some of the key factors to consider when deciding what level of resolution you need:
- Cost: Generally speaking, high-ground resolution and GSD costs more money to produce (and purchase), whereas lower-resolution images tend to be cheaper or even free.
- Availability: Today, thousands of public and private satellites constantly capture images of Earth’s surface. These satellites are equipped with sensors, each offering distinct capabilities. For instance, Sentinel satellites regularly acquire medium-resolution images (10-meter resolution). On the other hand, satellites like Pleiades from Airbus provide very high-resolution images (50cm) but visit the same location less frequently and may not cover all regions worldwide.
- Storage and computing: The higher the resolution of the image, the more storage and computing power are needed to process it.
- Area coverage: Do you want your map to show an entire country, an individual city, or just a single street? The area coverage you’re seeking will affect the kind of ground resolution needed.
Different resolutions for different purposes
When building a GIS map, you can choose between medium and high-resolution satellite images. None of these options is inherently better than the other – your choice will depend on the needs of your project.
Use of medium ground resolution GIS maps (~ 10m)
Medium ground resolution GIS maps (~10m) are valuable tools in the telecom industry and simulation & training sectors. Here are some examples of their use in these fields:
- Network Planning: Medium-resolution GIS maps help telecom companies plan their networks by identifying suitable locations for cell towers, factoring in population density, terrain, and potential interference sources.
- Coverage Analysis: GIS maps enable telecom operators to visualize and analyze coverage gaps, helping them prioritize network expansion and upgrades.
- Line-of-Sight Analysis: Medium-resolution maps are useful for determining line-of-sight connections between cell towers, ensuring optimal network performance and connectivity.
Simulation & Training:
- Emergency Response Training: Medium-resolution GIS maps can be incorporated into training simulations for emergency responders, helping them navigate and plan resource allocation during crisis scenarios.
- Military Training: GIS maps provide realistic environments for military training simulations, allowing personnel to practice navigation, terrain analysis, and tactical decision-making.
- Flight Simulations: Medium-resolution maps can be used to create realistic flight simulators, giving pilots the opportunity to practice navigation, takeoffs, landings, and emergency procedures in a safe environment.
- Urban Planning Simulations: GIS maps are essential in urban planning training programs, enabling trainees to analyze land use patterns, population distribution, and infrastructure development in a simulated environment.
Use of high-ground resolution GIS maps (~ 1m)
High-resolution GIS maps with a 50cm resolution offer even greater detail and accuracy, which can be advantageous in various industries. Here are some examples of their use in the telecom industry and simulation & training sectors:
- Micro Network Planning: High-resolution GIS maps enable telecom companies to plan micro networks, such as small cells and distributed antenna systems with precision by identifying optimal locations based on building layouts, urban features, and population density.
- Precise Coverage Analysis: The increased detail in 50cm resolution maps allows for more accurate coverage analysis, helping telecom operators to identify and address dead zones and weak signal areas.
- Infrastructure Management: High-resolution maps can help telecom companies monitor and manage their infrastructure, including the precise placement of fiber optic cables and equipment maintenance.
- 3D Network Planning: Using high-resolution GIS maps, telecom operators can interact with detailed 3D models of urban environments, which can help optimize the network performance in complex cityscapes.
Simulation & Training:
- Detailed Emergency Response Training: High-resolution GIS maps provide a more accurate representation of real-world environments for emergency responders, allowing for improved navigation and more effective resource allocation during training scenarios.
- Tactical Military Training: The increased detail in 50cm resolution maps enhances the realism of military training simulations, enabling personnel to practice navigation, reconnaissance, and target identification with greater accuracy.
- Advanced Flight Simulations: High-resolution maps can be used to create very realistic flight simulators, giving pilots the opportunity to practice navigation, terrain recognition, and precise landings in a safe environment.
Suggested: How satellite images are used to create 3D models
LuxCarta provides maps at the ground resolution you need
Every GIS map is unique, and your needs will vary significantly depending on the purpose of your project. At LuxCarta, our experienced teams can provide maps for your GIS projects at a wide variety of scales and spatial resolutions – down to 50cm. We utilize satellite images from various sources, ranging from 10 meter resolution to 50 centimeter stereo images, allowing us to customize your maps – and their level of detail – to meet your specific requirements.
Contact us today for support in creating maps for your project.