The phrase "are practically invisible from" is correct and usable in written English.
It can be used to describe something that is difficult to see or notice from a particular viewpoint or distance.
Example: "The small details of the painting are practically invisible from the back of the gallery."
Alternatives: "are nearly undetectable from" or "are almost unseen from".
Most garages don't have indirect lighting, or hidden pipes and sprinkler systems, or railings made of steel cable so thin that it is practically invisible from a few feet away — an innovation that leaves the cars looking as if they were parked at the edge of a cliff.
Who's got a billion dollars?" Since the school closed in 2002, the hall, which actually takes up most of the building, though it is practically invisible from the outside, had been used mostly for the church's annual Christmas pageant.
The flames from these fuels are practically invisible and if the fuel is spilled near the flames, this can result in a fire catching and spreading very quickly.
For much of the movie, the children (Teri and Vincent have two) are practically invisible.
Of course, the fact that atheists are practically invisible makes them less vulnerable.
Russian federal troops are practically invisible in Chechnya, confined to a single base east of Grozny.
And they are practically invisible,'' says Edwin Visser, country director of the Swiss NGO Medair in Jordan.
Because signs of the artist's hand are practically invisible, you could at first mistake her postcard-size pictures of awesome cloud formations for photographs shot from the window of an airplane.
Reading Anna Karenina again, I see that it's more extreme than that; urban buildings and landscapes are practically invisible, whereas the countryside is described in exquisite detail.
As of 2005, the smallest such devices commercially available measured 0.4 mm × 0.4 mm, and is thinner than a sheet of paper; such devices are practically invisible.
