Getting a smooth zoom between slides

[PeterWalmsley]

I'm wanting to make a smooth zoom as I go from one slide to the next but although I have linear zoom set, the resulting overall zoom speeds up and slows down. In the attached file I have 6 slides to show the problem.
(Note that I cannot just zoom out from one 'master' slide. I need the separate slides there to allow the individual pictures to appear.)

As a more general problem, even a long linear zoom restricted to just one slide seems to speed up as it runs. Any advice anyone? Thanks

Zoom test.zip

[Lin Evans]

Hi Peter,

Zooms are a tool which are designed to work within a slide, not between slides. There may be a way to do what you are trying to accomplish, but to help you design your show, it's necessary to see the project. If you will click on "File" "Create Backup in Zip" and post the resulting zip file then I will look at your project and help you design it to get the smooth result you are looking for.

You have said a "magic" word in your description of a "single slide" with linear motion. "Seems to." The issue is that the linear slide is absolutely linear, but the human brain doesn't interpret it that way. As the image gets smaller, we perceive it as zooming quicker when it indeed is zooming at a very constant speed. To correct for your own "perspective" there is a checkbox on the Common Tab in Objects and Animation called "Perspective Correction for Zoom." Click this and observe a simple zoom out and zoom in and you will perceive that it is linear when ideed it compensates for you perception by actually slowing down the zoom out and speeding the zoom in accordingly.

Best regards,

Lin

[jt49]

There is a much more sophisticated solution shown by Jean-Cyprien by placing key frames outside the slides' time intervals, see here. Nevertheless, this is only a workaround. What we really need is the feature of linking images and animations across slides that hopefully is still on Igor's to-do-list, see here.

Regards,

jt

[Guest Yachtsman1]

You could use your base slide as a master, then add the other objects as PNG files to come in at the correct sequence. Set the zoom to the master, then play around with the other objects timing & size.

Yachtsman1.

[denisb]

To correct for your own "perspective" there is a checkbox on the Common Tab in Objects and Animation called "Perspective Correction for Zoom." Click this and observe a simple zoom out and zoom in and you will perceive that it is linear when ideed it compensates for you perception by actually slowing down the zoom out and speeding the zoom in accordingly.

I don't agree Lin.

I made a zoom of 3000 (For PTE from 100 to 300000) and click on "Perspective Correction for Zoom." doesn't work.

I found a workaround (http://www.diapositif.net/forum/viewtopic.php?f=6&t=37185)

You can see how I do this zoom: http://www.diapositif.net/forum/viewtopic.php?f=35&t=38457

Denis

[Lin Evans]

Hi Denis,

What is it that you do not agree with? When you say it "didn't work" do you mean it did nothing or that it did not do what you expected?

here is a quick sample to see the difference in what a linear zoom and perspective zoom does - how one interprets it is another issue entirely and may depend on individual perceptions.

http://www.lin-evans.org/demo/comparezooms.zip

Remember, zoom in PTE is designed to work within a slide and not between slides. To accomplish smooth zooms between slides requires work-arounds as you have demonstrated in your tutorial. Many years ago I demonstrated what I called an "infinite" zoom where multiple images were matched so that the ending zoom in on slide one matched the field of view and focal length of the starting zoom for slide two and so on. The zoom was from a wide angle photo of a tiny object to a full macro view of the same object. This appears to be what you have done in your sample tutorial, but not being fluent in French I'm not absolutely certain of this.

Best regards,

Lin

[PeterWalmsley]

Many thanks for all the suggestions folks. It'll take me a while to work through these!

I have another show, not connected with this issue in which I'll try the perspective switch.

Lin, the project file you suggested is now attached.

.

Kind regards

Peter

Zoom test_Jul6-2014_23-14-29.zip

[jt49]

Part of the sequence using Jean-Cyprien's method.

Regards,

jt

Zoom-J-C.zip

[denisb]

Hi Lin

an example with frames :

Linar zoom

Perspective correction for zoom

What I should be glad to see if i thick "Perspective correction for zoom"

May be i'm wrong.

Best regards

Denis

zoom.zip

[Lin Evans]

Hi Denis,

I agree that your keyframed version is much more realistic than the perspective zoom in terms of keeping the perception of linearity constant. The question I have is how you arrived at the proper ascending increments which appear to offset the normal linear motion nearly perfectly? Regardless of how I adjust the "slope" of the linear curve, I can't seem to duplicate what you have done,

You have done a very nice job of providing a realistic constant zoom.

Best regards,

Lin

[Igor]

Hi Peter,

Try to use "Pan Z" parameter in "3D parameters" window.

I think it should give the result which you need.

"Perspective correction for zoom" simulates what can be done with "Pan Z".

You can apply "Pan Z" parameters for two key frames of each image object.

[jt49]

Again we have the situation where two more or less independent problems are discussed in a single thread:

1. Zoom (or any other animation) across several slides (the question of the original poster)

2. The question how perspective correction for zoom should work.

My example in post 8 refers to problem 1. This post includes a remark on Denis' example on correction for zooms.

Denis' example includes a nested group of 11 rectangles whose sizes decrease exponentially (by a factor of 2 from step to step with an overall zoom of 102400%). Linear zoom in PTE really is linear. So, what we see in the first part of the example is quite natural. What Denis wants to see (third part of the example) is a visually linear growth of his exponential rectangles. So what he asks for is just a standard exponential zoom. Part 2 of the example shows PTE's option "Perspective correction for zoom". This function is even more extreme than a standard exponential growth. Here we see exponential growth while the time points run following a geometric series. So in Denis' example, the zoom starts slow and ends up very fast.

Which kind of zoom is to prefer? When using zooms from 100% up to say 300% (the range that I normally use for normal images), the given perspective correction isn't that bad. Question: Who normally uses zooms from 100% to 102400%?

Regards,

jt

[denisb]

Hi,

I write about big zoom because Peter in his first post write about this problem.

I use important zoom in slideshow when i use Google Earth to show where the pictures where taken.

I think that for zoom the best is an exponentiel variation of zoom versus time in all cases.

Of course when the variation is small (may be 99% of all the zooms made in PTE), the exponentiel can be linearized and the linear zoom is sufficient.

Denis

[PeterWalmsley]

Seems to have been an interesting topic folks and thanks for all your replies.

Igor, the Pan Z approach is a little smoother but not really good enough.

JT - your example does work, but I don't understand what you've done! Can you explain in some more detail where and how you are setting the parameters on the timeline?

Thanks

Peter

[jt49]

JT - your example does work, but I don't understand what you've done! Can you explain in some more detail where and how you are setting the parameters on the timeline?

I'll try to do my best without writing a book. The attached project shows the case of a single image that is animated across several slides (here 3 slides) using 2 key frames. Your example is slightly more complicated but can easily derived from the method provided here (see also my post 8). Here we see an image (SD_blur) with a combined pan and a zoom (both with speed options 90/90 (acceleration with smooth stop)) starting in slide 2, and which ends within slide 4. The simple trick (as far as I know invented by Jean-Cyprien) works as follows: You insert the same image (here: SD_blur) into all three slides (2, 3, and 4) using 2 key frames. For animation start and end, insert corresponding values for positions and zooms. Then run through all starting key frames, and enter positive or negative values (milliseconds!) into the boxes 'Key frame time' in a way that in all slides the absolute start times coincide. In my example we see: 00:06.150. Do the same with the end times, in my example: 00:20.750. That's it

This is a kind of workaround. During execution, the animated image is loaded and processed 3 times. Not elegant, but it works. I have been asking for a long time to see a better mechanism to link images and their animations across slides. Let's see what will happen.

Regards,

jt

ZAS_2.zip

[PeterWalmsley]

Thanks jt. Working my way through your instructions with my more complicated sequence but looks like it should work.

Regards

Peter