You can do it by creating a group for each location, so users of the same group can see assets in that location.

Have a look at this question, it might help..%

You can do it by domains, But you have to know really well all the fields and how you have to filter them.

You can see an example of this on Sales Module, there is a group names See Own Leads that filters sales by user, so a user that is in this group can't see other Leads.

To see how they achieve this follow these steps;

1. You have to enable Technical Features on the user who is going to configure this. Settings>Users. Select the user who is going to have the technical features and in Access Rights enable Technical Features
2. Refresh your browser.
3. Go to: Settings>Security>Record Rules look for Personal Orders and see the domain: ['|',('user_id','=',user.id),('user_id','=',False)]

This is enabled for the group Sales / See Own Leads so they can see only the orders where user_id is the same as their user.id or user_id is False.

You can do something like this.

It doesnt work on Odoo 7. By doing so to the accounts the user will be locked to create / save changes.