"copy_to" into an array/acceptable geo_point format

I have two individual fields namely,

{latitute: 29.47
type: long}
{longitude: -98.53
type : long}

I want to create a single geo-point field named "location" out of the two above mentioned fields.
I tried using "copy_to" command but it doesn't give me the data that is in the acceptable "lat/lng" format for the geo_point.
How should I combine the two fields in order to get an acceptable geo_point format?

Ideally, do it during index time. You can use something like Logstash.