The quality of a polyline can be described in the following terms:

The number of points that make up the polyline
:   The more points there are, the smoother the polyline (especially in curves).

The floating-point precision of the points
:   Points are specified as latitude and longitude values, which are
    represented in single-precision floating-point format. This works well for
    small values (which can be represented precisely), but precision decreases
    as values increase because of floating-point rounding errors.

## Specifying polyline quality

When you call the `ComputeRoutes()` method, you use a
[`PolylineQuality`](https://developers.google.com/maps/documentation/routes_preferred/reference/rest/v1alpha/TopLevel/computeRoutes.md.txt#polylinequality)
enumeration value to specify the quality of the polyline.

Use the `HIGH_QUALITY` value when you want to create a polyline composed of the
maximum number of points, to produce a polyline of the highest resolution. This
increased quality comes at the expense of response latency.

Use the `OVERVIEW` value when you want to create a low-resolution overview of
the route, which is a polyline composed of a minimal number of points. This
option produces responses with the lowest latency.

### Example

The following example demonstrates how to set the polyline quality in the
request body.

```
{
  "origin":{
    "location":{
      "latLng":{
        "latitude":37.419734,
        "longitude":-122.0827784
      }
    }
  },
  "destination":{
    "location":{
      "latLng":{
        "latitude":37.417670,
        "longitude":-122.079595
      }
    }
  },
  "polylineQuality":"HIGH_QUALITY"
}
```