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Perspective Tool
I have difficulty using the perspective tool.  After adjusting one side, I try to adjust the other side but the first one moves.  Is there a way to anchor the corners so you can go to another one without the first one moving?

Thanks in advance for any advice.
As far as I can tell the other three corner handles don't move when you drag the fourth one?

Can you make a screenshot? Are you using forward or backward(corrective) mode?
Quote:...After adjusting one side, I try to adjust the other side but the first one moves.

I tried always to reproduce that, but can only get one handle moving.

Edit: After looking at the video again, Is the problem that the handles are outside the points you really aim at transforming? Adjusting the 'shape' of the transform moves everything inside the grid.

Try this video, see if your procedures/settings differ. 2 and a half minutes duration.

1. Perspective transform on the canvas
2. Perspective transform on a selection
3. Perspective transform - backward mode

edit: ...or are you trying to do something like this
that uses a plug-in but can be done by transforming a selection.
If you wait for Gimp 2.10 (or try Gimp 2.9.5) there is a new 'handle-transform' tool which allows you to select 4 points and drag around to deform
Sorry it took me so long to respond.  Was out with family.  I could not find the specific image I was working when I posted my problem with the perspective tool.  Today, I am not having trouble with the corners remaining where they are stationed but I cannot accomplish what I want to do.  This is similar what I was trying to attempt.  How to reset an item such as a plate which is being looked down upon  to one which is being looked at eye level?  No matter how I manipulate the image, I am not able to do this.  Also, I really do not understand the function difference between the forward and backward settings.  Maybe I am using the wrong one.    
The "corrective" mode is typically use to fix photographs where verticals aren't parallel because the picture has been taken with the camera pointing upwards. So you indicate what should become rectangular once the transform is applied:


However, I wonder if you aren't looking for something impossible: the Perpective tool can change the shape of things but not your point of view. In real life, if you look a the plate from a different angle, you see things that you couldn't see from the previous point of view, and there are other things that you can no longer see. And the Perspective tool cannot do anything about it, because it can't invent the missing pixels.
A little like a previous post, dealing with representations of solids, it is all about shading.

For a plate, this animation rotated 5 deg to 30 deg and light from top right, gives some indication of various shadings. Very annoying, so see:  - works on most browsers. (but not my slimjet - dumb thing)

For a front view, I think all is needed is scale the image vertically, how much depends on you, but this is from 300pix high to 100 pix. - nothing special there. 

But then, the new view should be showing part of the underside of the plate. Paint it in to suit. All depends on the lighting but for a small image like that, a plain colour should be ok. 

Thank you Ofnuts and Rich for your information and suggestions. I will practice some more with the perspective tool to get familiar with it.
Thank you Ofnuts and other administrators. Ofnuts' 3 photographs under "corrective" mode and Rich2005 video has given me some new insight in use of perspective tool.
Yash Pal, They are really knowledgeable about how Gimp works here. I had tried to find some info on the perspective tool before and failed. I am very grateful that help is so readily available here.

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