Best way to film a straight shot?

What's the best way to measure a straight shot? Do you know of any technical way of doing this?

Basically filming parallel to an object (or someone facing the camera in a wide shot).

Thank you.
If you want to get high tech there are lasers that will tell you how far away an object is.
Some cars use these for cruise control and will slow down if they get to close to the car ahead.

But you are way behind on your finances. Sounds like you need something low tech such as tape measure.
right now:

70% money
30% make content that people will like

Ummmm.... If you make content people like wouldn't that make more money? So if you're really in it for the money you should be "selling out" and making light entertainment (comedy, dramedy, etc.) or action/thrillers/super-heroes/sci-fi/fantasy. I guess the horror genre makes money as well. If you're really in it for the money get into advertising, although the burnout rate is fairly high.
i think horror is where it's at for the low budget money.
it's unfortunate i don't like horror.

Agreed on all points.

I discovered it's also the easiest way to get into a fest. There are so many horror fests out there even the top ones are short of content. When I entered a little short thingy into one of the world's top ten horror fests, I got in easily but I struggle to get into more mainstream ones.

Makeup, couple of shaky shots, a story with a beginning / middle / end, a bit of sound (mostly foley) and I was in. I didn't even need to send it off to a sound pro because the fest is so forgiving.

Only issue is I'm not really a horror guy...
i think horror is where it's at for the low budget money.

Yes and no! The low budget horror genre is a specific, limited marketplace, although undeniably a potentially very profitable one. The problem is that because it's very low budget, relatively easy to make and potentially very profitable, it's a magnet for all sorts of filmmakers, even those not really interested in the genre. It's therefore a severely over saturated marketplace. While that's not a problem as far as film fests are concerned, simply because more film fests will always spring up to cater for the demand from filmmakers, it is a problem as far as commercial distribution or monetisation is concerned because that's driven by the spending power and number of consumers, not the demand from filmmakers.