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ERDDAP > convert > Interpolate

Interpolate Values From Gridded Dataset Values

This converter efficiently interpolates values from a gridded dataset's values. As such, it is particularly useful for researchers working with animal track data (e.g., the IOOS Animal Telemetry Network (external link)). This converter takes in a table with latitude, longitude, and time columns (and perhaps other columns) and returns a table with additional columns with interpolated values based on the user-specified Request CSV with datasetID/variable/algorithm/nearby combinations (for example, jplMURSST41/analysed_sst/Bilinear/4 ). In all cases, for each latitude, longitude, and time point that you provide, the converter finds the specified number of nearby values from the specified datasetID/variable, then applies the specified algorithm to create the interpolated value.

Few people will routinely use this web page. Instead, most users will write and/or use a script which uses this web page's underlying web service.

The table with time, latitude, and longitude columns: ?
Request CSV: ?
   Options:    
File type:

Notes:

 


Want To Do Conversions from within a Computer Program, Script, or Web Page?

The form on this web page helps humans generate a request URL that is sent to ERDDAP when the human presses the Convert button. However, you can bypass this form by generating the URL by hand or in a computer program or script, and submitting the URL directly to ERDDAP. A sample request URL is
https://erddap.emodnet-physics.eu/erddap/convert/interpolate.htmlTable?TimeLatLonTable=
time%2Clatitude%2Clongitude%0A
2020-01-01T06%3A00%3A00Z%2C35.580%2C-122.550%0A
2020-01-01T12%3A00%3A00Z%2C35.576%2C-122.553%0A
2020-01-01T18%3A00%3A00Z%2C35.572%2C-122.568%0A
2020-01-02T00%3A00%3A00Z%2C35.569%2C-122.571%0A
&requestCSV=jplMURSST41%2Fanalysed_sst%2FBilinear%2F4 
(That has line breaks inserted to make it easier to read, but it is really just one long line.)

URL Length - Note that as the amount of data in the TimeLatLonTable increases, the request URL becomes very long. Because Tomcat has a default limit of 4096 characters per request URL, this converter is limited to 100 rows of input -- 100 rows is the most you can reliably request at one time. Even with this limit, this converter is much more efficient than making a separate request for each source Time Latitude Longitude value because bulk requests have 1/100th the network overhead and also get the data from the source dataset much more efficiently (often almost 100 times more efficiently).

Percent Encoding - The TimeLatLonTable and requestCSV parameter values in the URL must be properly percent encoded (external link): all characters other than A-Za-z0-9_-!.~'()* must be encoded as %HH, where HH is the 2 digit hexadecimal value of the character, for example, a space becomes %20. Characters above #127 must be converted to UTF-8 bytes, then each UTF-8 byte must be percent encoded (ask a programmer for help). There are websites that percent encode and decode for you (external link).


 
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