Planet Tile Streaming FAQ

Planet Tile Streaming FAQ

What is a tile?

A tile is a 256x256 pixel image (a “Tile”) that represents a certain portion of the earth at a particular zoom level.  Web applications stream many tiles to your browser or application to display a ‘slippy map’ that can be moved around (panned) and zoomed in and out.  Tiles are an efficient way to show images in interactive applications like Planet Explorer, QGIS, ArcGIS Pro or any other application that supports standard  WMTS or XYZ API tile services.  

How Big is a Tile? 

The area of land (measured in meters) that a tile represents changes a lot as you zoom in and out, and a little bit as you pan North and South.  Your current zoom level and the meters per pixel is displayed in the Planet Explorer footer. The table below demonstrates how tile size varies as you zoom in and out.  Please refer to this link for more information on how tile size can vary by latitude.  

Level

# Tiles to 

cover the Earth

Tile width

(° longitude)

Meters per pixel (on Equator)

Examples of Features this Size

0

1

360

156 412

whole world

1

4

180

78 206

 

2

16

90

39 103

subcontinental area

3

64

45

19 551

largest country

4

256

22.5

9 776

 

5

1 024

11.25

4 888

large country

6

4 096

5.625

2 444

 

7

16 384

2.813

1 222

small country, US state

8

65 536

1.406

610

 

9

262 144

0.703

305

wide area, large metropolitan area

10

1 048 576

0.352

152

metropolitan area

11

4 194 304

0.176

76

city

12

16 777 216

0.088

38

town, or city district

13

67 108 864

0.044

19

village, or suburb

14

268 435 456

0.022

10

 

15

1 073 741 824

0.011

5

small road, highest native-level zoom for PlanetScope

16

4 294 967 296

0.005

2.5

street

17

17 179 869 184

0.003

1.2

block, highest native-level zoom for SkySat

18

68 719 476 736

0.001

0.596

buildings, trees

19

274 877 906 944

0.0005

0.298

local highway and crossing details

20

1 099 511 627 776

0.00025

0.149

A mid-sized building

 

Credit: https://wiki.openstreetmap.org/wiki/Zoom_levels

What is the tile-caching policy? (Is it different on Explorer and Integrations) 

The tile services display a cache time in their response headers. This is currently twenty fours hours for Basemaps and scenes. How third-party clients deal with this is further dependent on the implementation. Tiles may not be cached for redirection.

What zoom levels are calculated against the quota? 

We track how many tiles customers stream at all zoom levels. 

At each zoom level, what is the geographic scale of a tile in terms of square kilometers? 

Planet uses the Mercator projection for our tile streaming services. This projection significantly scales (particularly near the poles), but has two advantages. It is a cylindrical projection; it always orients north and south up and down and east and west are always left and right. It is a conformal projection, it preserves the shape of smaller objects.  

What is the highest zoom-level by products?

SkySat is zoom level 17, PlanetScope is zoom level 15, and Basemaps vary based on the imagery they are based upon (mostly 15 but some are ~17). As noted above, we allow by user request zooming above this.

However, there are a few places where our Planet integrations (QGIS & ArcGIS) differ. We allow customers to zoom past native resolution. So users can zoom past level 17 for SkySat, 15 for PlanetScope, and 15 for Basemaps. This is helpful for GIS use cases that often involve a lot of digitizing over imagery. However, no additional tile requests are needed here for zoom levels past the native max resolution.

How many tiles are loaded in one session?

Hypothetical use cases to provide examples of how many tiles are used when performing common tasks with Planet Explorer. 

Example Use Case 1: 

Civil Government customer inspecting water reservoir level. 

Open Planet Explorer, select a Basemap, draw a 10 sq km AOI and inspect that area of the basemap. 

In total this uses about 50 tiles.   

Example Use Case 2: 

Ag customer examining part of a field after a storm for damage. 

Open Planet Explorer, select daily imagery, searching for an address/location, 

pan to find the right area on the farm, (panning around and zooming in and out consumes the most tiles)

drawing a 0.01 sq km (1 hectare) AOI and selecting between(10+ different images to pick the best, cloud free image to examine a wind event. 

(comparing different images consumes very few tiles)

In total this uses about 500 tiles.

Example Use Case 3:

This is a hypothetical example: 

Intelligence customer examining a month worth of imagery to examine a 500 square kilometer peninsula.  The customer zooms in, out, looks at imagery over a whole month, panning, zooming frequently to examine change over time.  The customer looks at a radar installation, a harbor, lighthouse and access roads for new groups of equipment.  

In total this uses about 2,000 tiles.

Does screen resolution affect the tiles that are loaded in one session? If so how many tiles would get loaded in one session for a standard screen resolution to a 4K to an 8K resolution?

Screen resolution affects the number of tiles loaded in one view. For example, a 4K resolution screen that is 4096 x 2160 pixels results in 135 tiles loaded in one view and an 8K resolution screen 7680 × 4320 pixel results in 506 tiles loaded in one view.

Are there any user restrictions?

Customers who purchase Basemaps may stream tiles they have purchased. Customers who have purchased access to our PlanetScope catalog may stream tiles from PlanetScope imagery. Organizations that have purchased Planet Tasking or SkySat archive may stream tiles from their collections or our catalog respectively.  

If two users access the same tile at the same time, does it count as one or two distinct tiles and can we track that uniquely?

Each user's streaming tiles are served and usage is recorded for all users individually. We record the source of the tiles, such as a Planetscope or SkySat image or the Basemap from which the tile is streamed.   

What is the tile service expiration time? 

Twenty four hours for Basemaps and Scenes, similar to the tile-caching policy.

Where can customers find their usage?

Customers may download a report of their usage at planet.com/account. Individual users may see their own usage while administrators may see usage for all users in their organization. Usage is calculated, generally, on a daily basis and posted to the accounts page.

 

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