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. If you’re not yet a member, join Which? to get instant access.Some other great sources of non-commercial, non-downloadable imagery are: Only logged-in Which? members can view our recommendations in the table below. So whatever you’re looking for from a sat nav app, we will help you find the best one for you. We'll also take a look at how sat navs apps with subscriptions and paid-for features match up against free ones. There are still some apps that aren’t up to scratch, with such poor audio and visual guidance that they’re useless.īut sat nav apps have improved in the past few years, and the best free sat nav apps will now guide you from A to B with brilliantly clear vocal and visual guidance, as well as advanced features that used to be reserved for pricey devices.īelow, we reveal some of the best free sat nav apps available, and what they have to offer. In the past, apps struggled to keep up – small phone screens made maps difficult to read, and smartphones simply weren’t fast enough to make the instructions useful. So if we recommend a free sat nav app, you can be confident it's a really good one. We put free sat nav apps through the same tough tests as paid-for apps or standalone sat nav devices.