Google Maps Elevation API Quotas

Litchi Mission in Google Earth Pro

Virtual Litchi Mission and Google Earth Pro

Virtual Litchi Mission is a software program designed for Litchi users and DJI drones. Litchi's Mission Hub allows users to plan and configure waypoint missions from the comfort of a home computer. VLM extends the capabilities of Litchi's Mission Hub so that a configured mission can be simulated in Google Earth Pro and test-flown before flying with the actual mission.

This ability of VLM to create and simulate a flight path requires the use of the Google Maps Elevation API. The Elevation API is a service that returns elevation data for a location on the earth, or sampled elevation data along paths. [Details]

Use of the Google Maps Elevation API is not entirely free. To use the Google Maps Elevation API, an API key must be obtained. To get this key, a credit card must be provided for any charges incurred. Limits may be placed on the use of the API key in order to prevent over-usage (and credit card charges). VLM uses a shared API key created by its author. If VLM's usage exceeds a predetermined quota, it will stop working for all users until the end of the current month.

Every VLM user has the ability to obtain and use their own API key. Doing so, will enable their use of VLM even when the shared API key of VLM has exceeded its quota for the month. While it is unlikely that one's own use of an API key will exceed any usage threshold, it is possible to place a quota on your own API key to limits it use. At the time of this writing, a $200 USD Google Maps Platform credit is available each month for each billing account. [Details] This document will describe how to configure a quota so that your usage can never result in a monthly charge from Google.

Google's current credit is $200 USD per month for the Google Maps Platform. This is equivalent to $6.45 per day.

$200 USD / 31 days per month = $6.45 USD per day of free usage

The cost of the first 100,000 API requests is 0.005 USD per request. This would result in 1,290 free API calls per day.

$6.45 USD / 0.005 USD = 1,290 free API calls per day

This value (1,290) may be configured as a daily quota in the Google API dashboard.


Google API Dashboard

Navigating to the Google API Quota Settings

Navigating the Google API dashboard can be less than obvious. Follow the steps below to navigate to the section where API quotas can be configured.

  1. Navigate to, then log into, the Google Maps Platform Dashboard.
  2. Select "Quotas" from the menu on the left.
  3. Select the desired project (if more than one) from the dropdown menu at the top of the dashboard. Mine is named "Drone". Yours may be named something else.
  4. Select "Maps Elevation API" near the top of the dashboard.
  5. Select the "Requests" down-arrow to display the request history.

Google API Request History

Configuring a Google API Quota

At this point you should be viewing a graph of your Google Maps Elevation API history similar to what is shown on the right. Each bar represents one day of usage. The Y-axis is the number of requests. If a quota is set, a dashed red line will be displayed showing that limit.

Scroll down until you see a small table listing the quota names and limits. The most important limit is the top one: "Requests per day". If you modify this limit to be what was calculated above (1,290), it will prevent the usage from ever exceeding the $200 USD free credit per month. To modify the settings, click on the pencil icon and change the limit.

Once your quota is configured you can be confident that your usage will never incur a cost.


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