Hi Larry,
thank you for your long letter.

At least I know now that I did not overlook an important fact in
using bitmaps.

--- In compass-users@yahoogroups.com, "Larry Fish" <lfish@...> wrote:
>
> Hi Guenter,
> Thanks for your letter.
> > after a long time of rest I have again reached a point
> > were I have to cry for help.
> Sorry you are having trouble getting your bitmap to align with the
plot.
> These tools are pretty complicated and take a bit of practice to
get them to
> work right.
> > The main problem/wish is to have a fixed topografic bitmap
> > which fits my cave, so no further zooming is necessary,
> > adjusting manually the position is ok, but I want to have a
> > bitmap, which fits my cave, if I use the scale of 100
> > Meter/cm, so that I don't have to rezoom it again and again.
> The scaling values that are contained in bitmap images are very
seldom
> accurate. On the other hand, the cave survey is generally much more
accurate
> since it is made up of dozens of hand measurements. For that
reason, Compass
> ignores the scale values you find inside a bitmap. As a result, the
process
> of matching a cave to a bitmap is done by re-scaling the image, not
the
> cave. When you set the cave's scaling to 100 Meters/cm your are
only setting
> it for the purpose of printing or display. It does not have an
effect on
> matching the cave to a bitmap.
>
> > First: Whenever I lock a bitmap, the bitmap shrinks on the
> > screen, where is the switch to stop that shrinking?
> Again, Compass adjusts the bitmap to fit the cave, not the other
way around.
> The bitmap shrinks because you have already zoomed the cave to a
different
> size/scale. When you enable the "Lock-Image-To-Cave" option, the
program
> realizes that you have changed the size of the cave and it resizes
the
> bitmap to match.

Ok understood, This was my failure!


> > Second: With my cave at a scale of 100 Meter/cm I tried to
> > prepare a topografic bitmap, which fits. But it does not. I
> > think, that some/thing/one changes the DPI or whatever. What
> > are the real conversion figures to adapt my bitmap? My
> > topografic bitmap has 4000*3000 pixel at 72ppi (28,346 pixel/cm).
> > 4000 pixel equals 5 km in nature. (At least this is what I can
see in
> > Photoshop)
> The values you see in Photoshop may not even be included in the
bitmap and
> so Compass does not even attempt to use them.
>

I was just confused, because Compass showed me a height a a width
in km of my bitmap.

> Here are the steps you need to take to adjust a bitmap to match
your cave.
> 1. Load the cave data into the Compass Viewer. Don't worry about
the cave
> scale factor at this point.
> 2. Load the bitmap into the Viewer using the "File -> Load Bitmap"
option
> from the Menu Bar.
> 3. Select the "File -> Adjust Bitmap" option from the Menu Bar.
> 4. Immediately turn on the "Lock-Image-To-Cave" option.
> 5. Now use the "Move Bitmap" buttons to move the Bitmap so the
location of
> the entrance matches the entrance on the plot of the cave.
> 6. Now adjust the Scale so the bitmap is the proper size for the
cave. This
> is hardest part.


Shure, I fully aggree ;-). And that started my thinking that I
might have overseen a major part. Because after each zooming step, I
have to move the bitmap again. Because of this zooming, my cave
entrie moves away from its proper point. I cant fix the cave entry of
the cave to the cave entry on the bitmap. So every zooming action is
accompanied by a moving action, over and over.


>I usually try to find something on the bitmap that is of a
> known size. For example, if it a topographic map, you can usually
find grid
> lines, a length of road, a lake or just any two land marks. If you
measure
> their distance on the topographic map, you will know how long they
should be
> in relation to the cave. Once you have identified an object of a
known size,
> select the "Tools -> Measure Distance/Angles" option in Compass.
This will
> allow you to measure the size of the object on the bitmap. If the
object
> measures too big or too small, adjust the Bitmap Scale in
the "Adjust Bitmap
> Background" window. Keep re-measuring and adjusting until the error
is very
> small.
>
>
>
> 7. Final step is to adjust the rotation. If you have used the proper
> Declination on all your survey files, the cave should be aligned to
True
> North. If the bitmap is also aligned to True North, then you won't
have to
> do any rotating. However, if the cave does not have any
declinations and the
> cave plot will be aligned to magnetic north and so you may have to
rotate
> the bitmap. Likewise, many bitmap images are not aligned to True
north. If
> that is the case, then you will also have to do some rotating.
>
>
>
> In all this process, you can use the regular Pan, Zoom and Rotate
options in
> Compass to position the cave and the bitmap where you want. Since
you have
> locked the cave and the bitmap together, changing the overall
rotation, pan
> and zoom position won't affect the relative position of the cave
and bitmap.
>
>
>
>
> 8. Once the Bitmap and the Cave have been adjusted to match each
other, you
> can now close all the "Tool" windows and navigate as would normally
do in
> Compass. You can zoom, pan and rotate, and the cave and bitmap
image will
> track each other. You can now set the overall Scale to any value
you want
> (including 100 meters/cm) and the cave and bitmap will print at
that scale.
> The value is set using the "Action -> Scale, Magnification,
Rotation" option
> from the menu bar.
>
>
>
> There are couple caveats with this process:
>
>
>
> First, very large bitmaps may be slow to update, particularly when
you do
> any rotations. This is dependent on the kind of computer you have
and the
> graphic card drivers. Your bitmap is 3000x4000, which is pretty
large. If
> the update rate is intolerably long, Compass offers you the option
of
> reducing the image size. Even a small reduction in size can speed
things up
> a lot. For example, cutting the size in half will increase the
speed by four
> times.

I am using a part out of an official topografic map, where I
exactly now how long a point is and what coordinates are were. That
is why I did not change it. It does not really remarkably slow down
my PC, so at first I can live with it.


> Second, there is a bug in the rotation routines that sometimes
causes shifts
> in the position of the cave relative to the bitmap. It only happens
under
> certain circumstance and I haven't' had time to track down the
problem.
> (Besides, I may just shift over to using OpenGL, which may be a
better
> solution.) In any case, be aware of the problem. You can usually
avoid it if
> you don't rotate the cave.
> > Btw. the Image Position shows always only the indication
> > "Ft." not "M.", but it really changes the values to Meter or
> > Feet.
> Yes, thank you. It is a bug and I have just fixed it. There is a
new version
> of Compass on the Internet with the problem fixed.
>
> Thanks again for your letter. I hope it helps you solve the problem.
> Larry
>

Thanks again for your letter. I hope it helps you solve the problem.
Larry

Thank you for your help.
I would like to report another small 'feature', which is not serious
at all: If I edit a bitmap and want to save it with a name,
say 'mycave', and I forget to explicitely write the suffix, the
software creates a file with 0 bytes in it, called 'mycave'.

So next time you might see our cave with an underlying topographic
map, saturated over and over by my drops of sweat.

Greetings
Guenter
www.hoelloch.de

> _____
>
> From: compass-users@yahoogroups.com [mailto:compass-
users@yahoogroups.com]
> On Behalf Of caveguenter
> Sent: Monday, February 11, 2008 3:53 PM
> To: compass-users@yahoogroups.com
> Subject: [compass-users] Load Bitmap Adjust Bitmap and so on
>
>
>
> Hi all together,
> after a long time of rest I have again reached a point were I have
to
> cry for help.
> The main problem/wish is to have a fixed topografic bitmap which
fits
> my cave, so no further zooming is necessary, adjusting manually the
> position is ok, but I want to have a bitmap, which fits my cave, if
I
> use the scale of 100 Meter/cm, so that I don't have to rezoom it
again
> and again.
>
> First: Whenever I lock a bitmap, the bitmap shrinks on the screen,
> where is the switch to stop that shrinking? I thought, that locking
> means just zooming the bitmap with the cave, _if_ I would do so. But
> it shrinks immediately, just by setting the 'Lock image to Cave'
check
> mark. (Version 5.07.8.29.243 of the Plot Viewer)
>
> Second: With my cave at a scale of 100 Meter/cm I tried to prepare a
> topografic bitmap, which fits. But it does not. I think, that
> some/thing/one changes the DPI or whatever. What are the real
> conversion figures to adapt my bitmap?
> My topografic bitmap has 4000*3000 pixel at 72ppi (28,346 pixel/cm).
> 4000 pixel equals 5 km in nature. (At least this is what I can see
in
> Photoshop)
> If I load it into Compass, the image size is shown (Adjust Bitmap
> Background) as 4000*3000 pixel and also is shown that this equals
6699
> (X) * 5024,3 (Y) Meters at a scale of 1.00. What has changed? And
> locking does shrink my bitmap (not the polygon) by a certain factor.
>
> Btw. the Image Position shows always only the indication "Ft." not
> "M.", but it really changes the values to Meter or Feet.
>
> Thanks
> Guenter
>