IINSERT command Image Correlation Scale bug

[Anonymous]

C3D 2017, I came across this bug while trying to insert ortho images using the IINSERT command.

I have .sid files I am trying to bring in, I type in IINSERT, browse to my file, and select Open.

The Image Correlation window opens.

Insertion point, rotation and scale all look good up to this point (see screenshot 1)

As soon as I switch to the Insertion tab, the scale jumps up to 1707.4893 (or some other random high number)(Screenshot 2)

Switching back to the Source tab updates the scale to match the scale on the insertion tab. (Screenshot 3)

Switching back and forth between the Source and insertion tabs increases the scale each time.

Even if I do not switch to the insertion tab (the first time) the image still does not come in correctly.

This link references an issue where the MAPIINSERT command does not recognize the world file if the path is longer than 128 characters, but I do not think that is the case, as my path is only 53 characters.

https://knowledge.autodesk.com/support/autocad-civil-3d/troubleshooting/caas/sfdcarticles/sfdcarticl...

If I IINSERT the images in using C3D 2016, and then import them using MAPWSPACE in C3D 2017, then they come in correctly.

Thank you for your time.

[Pointdump]

DS,

"Switching back and forth between the Source and insertion tabs increases the scale each time."

Interesting observation.

I haven't had much luck with MAPIINSERT. It seems iffy at best. Did you try changing the units to match the drawing units?

Dave

[Anonymous]

Units do match the drawing units, and it still does it.

[Anonymous · Accepted solution]

I figured out what the issue is.

In the drawing settings, in the Units and Zone tab, if the Imperial to Metric coversion is set to International Foot, that is when the Image Correlation scale changes everytime you switch tabs.

If you set the Imperial to Metric conversion to US Survey foot, the scale remains the same.

[Pointdump]

DS,

"...increases the scale each time."

How much does the scale increase?

Dave

[Pointdump]

DS,

Does it increase by a multiple of 1707.4893 each time? Or another number? Reason I'm asking is it would be nice to know the mathmatical pattern.

Also, what coordinate system are the MrSID's in? What coordinate system is your drawing?

Dave

[Anonymous]

Here's a link to an article about the differences between US Survey and International feet.

POB US Survey Foot / International Foot

[Anonymous]

Dave,

When the Image correlation "Units for Insertion Point & Density" is set to inches, it jumps to 1701.6981 the first time, 2,895,776.3549 the second time, 4,927,737,004.3438 the third time.

When that same setting is set to Feet, in jumps to 20420.3767 the first time, 416,991,784.895 the second time, and 8,515,129,335,003.763 the third time.

I have my ortho drawing set to UTM83-12. 

The .sid files are in a local coordinate system created by our county survey team, I believe.

The wierd thing is, on another drawing, with the same settings as the other one, I had to set the Imperic to Metric conversion to International foot to get it to come in right, instead of US Survey Foot.

I am confused...lol

[Pointdump]

DS,

So it's squaring the Scale Number each time. That's just SO weird! 20,420.3767 divided by 1701.6981 is 2 PPM short of 12. But why it's tossing out that first scale number is baffling. What is the pixel size of your MrSID?

Dave

[Anonymous]

The Image Correlation window says the image density is 6.5617x6.5617 pixels per unit. Is that what you were asking?

Another thing we noticed here in the office... In the drawing settings menu, if we leave the option to "Set AutoCAD variables to match" checked, it changes our units to US Survey Foot, no matter what we set the units to. Which makes sense, but I have been having to set my drawings to International foot to get the IINSERT command to insert my sids correctly. When I uncheck this option, I set my units to feet, leave the Imperial to Metric conversiont set to US Survey Foot, and everything comes in just fine.

So, I don't understand why it's doing what it's doing, but I seem to know how to get it to do what I want it to...

[Pointdump]

DS,

Just looking for any correlation to increase understanding.

Your screen shot shows you are using a Metric Coordinate System, but your Drawing Units are Feet. UTM83-12 comes in 3 flavors, Metric, International Feet, and Survey Feet.

One thing I've noticed is that Drawing Units will remain in whatever Template you started your drawing with. If you start with an International Foot Template and change your Coordinate System to, say, a State Plane System in US Survey Feet, your Drawing Units will remain in International Feet.

Dave

[Cadguru42]

I wonder if the bug where the MAPIINSERT command ignores an embedded world file UNITS is at play here? If you're using an external world file, I don't believe it applies. 

[Anonymous]

Dave,

I have tried using the US Survey Foot coordinate system, but the images always come in wrong. The only way I have been able to get them to come in correctly is to use the Metric coordinate system, even though my units are in feet.

I don't think I've tried the Internation Foot version of UTM83-12. I'm not sure what that will do.

[Anonymous]

Guru,

When I download the .sid file from the county website, it also downloads a separate file, a .sdw, along with it. Which, as I understand it, is the world file associated with the .sid.

[Pointdump]

DS,

I've never used a MrSID file. Can you post the link? I'd like to play with it.

Dave

[sterling.woodruff]

Hi! I've run into your same problem with it randomly scaling when inserting the image. I checked my units and tried what you said, but still with no luck. Any suggestions? When using data connect it places it just fine, however I would like to just insert the image and not have to worry about the data connect.

[Pointdump]

Sterling,

Can you post your problem image and what Coordinate System you're using?

Dave S

[CWI-HDS]

I'm using Civil 3D 2021.  I had the same issue where the scale increased every time I switched tabs on the Image Correlation dialogue window when bringing in an ortho image.  I checked the Imperial to Metric conversion and it was already set to US Survey foot.  My fix was to open the Drawing Units dialogue (command: UNITS), then set Insertion scale to Feet.  If it is set to US Survey Feet or Unitless, the scale bug in the Image Correlation dialogue occurs where it increases every time you toggle between tabs.