In practice, this means that the local time in these time zones changes when DST begins and ends. For example, Eastern Time (ET) refers to Eastern Standard Time (EST) or Eastern Daylight Time (EDT), depending on which is currently in use. The time zones in the contiguous US are often referred to by their generic name, without making a difference between standard time and Daylight Saving Time designations. Generalized Time Zones in United States Time Zone Abbreviation & Name Since Howland Island and Baker Island constitute the world's westernmost landmasses in relation to the International Date Line, making them the last places on Earth where any date exists, they are sometimes assigned a theoretical 12th time zone called Anywhere on Earth (AoE). As neither Hawaii nor the 5 dependencies use Daylight Saving Time (DST), there are only 6 corresponding DST time zones. In addition, Alaska, Hawaii, and 5 US dependencies all have their own time zones. The contiguous US has 4 standard time zones. However, adding the time zones of 2 uninhabited US territories, Howland Island and Baker Island, brings the total count to 11 time zones. There are 9 time zones by law in the USA and its dependencies. Time Zones Currently Being Used in United States Offset Business Date to Date (exclude holidays).Regardless of what piqued your interest in finding up-to-date satellite imagery in the first place… I hope you find what you’re looking for. If you decide you’re going to pay for imagery, do your own homework some of the best deals you find are from independent pilots who will fly aerial or drone imagery for you on an hourly basis! Last time I checked, there were over 20 different browsers for looking at Landsat 8 imagery alone and that was more than three years ago! There are also plenty more aerial and satellite imagery providers-I simply listed some of the largest ones. There are plenty of other places to get access to some of the datasets I mentioned above-especially the free ones. If you’re new to this world, the first thing to know is that you’re almost certainly going to have to speak with a salesperson-there’s no such thing as simple, transparent pricing in the satellite and aerial imagery world (at least not yet).įor slightly lower resolution but higher frequency imagery:įor aerial imagery in the U.S. We run into this situation quite frequently at Azavea, so we’ve gotten to know many of the providers over the years. Lastly, there’s the difficult case of needing high resolution, recently collected imagery (especially if you plan to derive commercial works from that imagery and need access to the raw files). That imagery can also be downloaded from either Earth on AWS or the Earth Engine Catalog-you can also browse when the most recent imagery was collected for each state (and at what resolution) at this free online coverage map hosted by ESRI. In the U.S., the USDA’s National Agricultural Imagery Program (NAIP) captures 1m/pixel or better imagery for the entire contiguous United States once every other year. Make sure you familiarize yourself with the data before downloading a lot of it!įor high-resolution aerial imagery, your options are much more limited. A warning: these are very large files and the imagery itself is lower resolution than what you might expect to see on a typical web map. MODIS (NASA’s satellite constellation which images the earth every 1-2 days)ĭata from all three of these satellite constellations can be downloaded for free from either Earth on AWS or Google’s Earth Engine Catalog.Landsat 8 (the USGS’s satellite which images the earth once every 16 days).Sentinel-2 (the European Space Agency’s constellation of satellites imaging the entire landmass of the earth once every five days). ![]() Here’s where things get interesting-we’ve written previously about the explosion of freely available, openly licensed, and constantly updating satellite imagery in our blog post, An Introduction to Satellite Imagery and Machine Learning. For larger-area basemaps, satellite imagery providers make more sense: and Australia and has a very simple user interface available through any web browser. For high-resolution aerial imagery, NearMap orthographics provide great coverage in the U.S. Rather than license imagery from Google that they’re, in turn, licensing from imagery providers, it usually makes more sense to go directly to the source. Google’s Maps API is notoriously stingy in this regard, with its terms of service even limiting your right to display content derived from Google imagery on a map that isn’t also provided by Google. tracing building footprints or other cartographic features), you should consider a paid option that allows for derivative works to be produced. ![]() If you’re considering deriving a commercial product from the imagery you’re browsing (e.g. ![]() Some other great sources of non-commercial, non-downloadable imagery are:
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