TerraColor NextGen Frequently Asked Questions
- What does "15-meter resolution" mean?
- Can I see individual houses or cars in NextGen imagery?
- How new is the NextGen imagery?
- What is true color imagery and why is it important?
- What does cloudless or cloud-free really mean?
- At what map scales can NextGen imagery be used?
- Does NextGen offer complete coverage of the globe?
- Does NextGen have imagery of Antarctica and the Arctic Ocean?
- Do you provide terrain/elevation data to complement the NextGen imagery?
- Do you provide a global water bodies mask to complement the NextGen imagery?
- Is NextGen available in Cloud Optimized GeoTIFF format?
- How is NextGen used in web mapping products?
- Does the GIS company Esri use NextGen?
- Is there a 10-meter resolution version of NextGen?
- What if I don't need the full 15-meter level of detail?
- What is an ocean mask and why is it used in NextGen's processing?
- Does NextGen offer global images with bathymetric ocean fill?
- Can NextGen be customized?
- How large is NextGen in file size?
- What is the easiest way to copy a subset of NextGen tiles from a larger set?
- Can I purchase NextGen imagery of a country or continent only?
- Can NextGen be downloaded via FTP?
- How large of a print can be made with NextGen?
What does "15-meter resolution" mean?
Resolution refers to the amount of detail in the imagery, and 15 meters refers to the ground dimensions of one pixel in the image. (So, one pixel covers a 15x15 meter patch of the ground.) This level of detail is sometimes called "medium resolution" and designed to create images of the complete globe all the way down to images of mid-size cities. Below is a full resolution snapshot of Singapore harbor:
Can I see individual houses or cars in NextGen imagery?
NextGen's 15-meter resolution does not provide enough detail to clearly see individual houses, cars, and similar smaller size features. For that, you need high resolution imagery, which is offered by other vendors.
How new is the NextGen imagery?
For much of the world the imagery dates are between 2014-2018. With our recent new release, we upgraded many key areas of the world with 2018-2019 imagery. For more details, see the Specifications page.
What is true color imagery and why is it important?
Most satellites image the earth in a variety of spectral bands (or wavelengths of light). Some of these are visible to the human eye (like green light) and some are not (like infrared light). A true color image is created when the image is built from the satellite's spectral bands corresponding to the red, green and blue wavelengths of light. Since the human eye is also sensitive to red, green and blue light, the NextGen image colors look "true" much the same as a person would see them from an aircraft. (Sometimes the terms "true color" and "natural color" are used interchangeably, but we prefer true color so there is no confusion.) Not all satellite images are true color, some vendors create false color images incorporating infrared bands, then manipulate the colors to try to make it look more natural (we call this "simulated natural color"). Since the colors cannot look truly realistic, sometimes you end up with strange artifacts like a blue patch in the middle of a desert where there is clearly no lake. This can cause problems in understanding the imagery, and it may not match well with other true color imagery of the same area.
What does cloudless or cloud-free really mean?
When evaluating products in NextGen's class, you'll often see the words "cloudless" or "cloud-free" used to describe the amount of clouds present in the imagery. In practical fact, products claiming to be "cloudless" do in fact have some clouds in areas with chronic cloud cover like the tropical equatorial areas or some oceanic island chains.
Many people think that all parts of the world have at least some perfectly clear "cloud free" days, but that is not the case. Building imagery with low cloud cover for those problematic areas requires piecing together parts of many scenes from multiple dates that have clouds in different parts of the imagery.
So, when we describe NextGen's cloud cover as "less than 0.5% globally" we mean that, on average, 99.5% of the pixels in the global coverage contain no clouds. Many large areas are 100% cloud free, while some other smaller areas may be only 90-95% cloud free due to persistent cloud cover. In addition, we never "paint out" clouds; 100% of the NextGen 15m imagery for land areas comes from real pixels in real images.
Does NextGen offer complete coverage of the globe?
Yes, unlike some other vendors, we offer off-the-shelf coverage of the entire planet with no gaps or holes. This makes NextGen perfect for virtual globe applications that require complete coverage of the earth.