AutoCAD Map 3D General Discussion

AutoCAD Map 3D General Discussion

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Contributor
lorrie.bundy
Posts: 19
Registered: ‎02-24-2003
Message 1 of 11 (777 Views)

Mr Sid image shifted 30 ft north

777 Views, 10 Replies
07-05-2012 11:24 AM

Hello all,

I have a MrSid image in my base map. The dwg setting is set to UTM survey ft coordinate system.

This image is shifted north approx 30 ft basd on comparison of position with shapefiles imported using Map3D 2010.

I have tried several methods to insert image:

1.Map | Image Insert | insertion units meters

2. xref a dwg with image inserted and drawings units: meters

 

I think the fundamental problem is that the image is treated like a block and the conversion factor is 3.2808. This works great for internaltional ft units, but not survey feet.

 

How do I change the default conversion factor to 3.28083333 to more accurately convert units from meters to survey ft?

I think the north shift is more obvious since the northing coordinate is 10x the size of the easting coordinate.

 

btw....I tried to use Data Connect but with the help of Autodesk help people, but we determined the large file size prevents using this feature. Othewise I would use SPC for drawing coordinate system and the conversion would be handled using proper GIS transformation tools.

Contributor
lorrie.bundy
Posts: 19
Registered: ‎02-24-2003
Message 2 of 11 (775 Views)

Re: Mr Sid image shifted 30 ft north

07-05-2012 11:41 AM in reply to: lorrie.bundy

a little more investigation shows that CAD uses conversion 0.3048 to convert from meters to feet.

If it used 0.3048006096, the 30 ft shift would be corrected.

I checked this using Image | Insert, viewing insertion coordinates and calculating conversion factor.

 

How do I set a different conversion value?

 

Thanks in advance.

Product Support
phil_borycens
Posts: 189
Registered: ‎10-25-2011
Message 3 of 11 (736 Views)

Re: Mr Sid image shifted 30 ft north

07-11-2012 10:28 AM in reply to: lorrie.bundy

Hi Lorrie,

 

Unfortunately, it seems that the conversion you are referring to is hard-coded in the program. I see two change requests related to MAPIINSERT and the way that it translates between units, and I have linked your case to those so that they receive further attention from our developers.

 

I have done some tests based on your posts, and I wonder if the issue here is the fact that there is no option for International Feet or Survey Feet in the Units drop-down of the MAPIINSERT Image Correlation dialog.

 

I wonder if the scale be changed from something other than 1:1 to correct this issue? I'm not sure, as I have been unable to reproduce your exact issue. If you want, I can enable a FTP site for you to provide me a complete dataset so that I can observe the issue and maybe provide other tips.

 

You mentioned using FDO as an alternative to MAPIINSERT, but your challenge was the size of the MrSID image. You can try this on a 64-bit system with at least 8GB RAM for good results, or you can try trimming and/or converting the image to another type. There are some great workflows for doing this in AutoCAD Raster Design, if you have that product - please see the following blog for more information:

http://bimontherocks.typepad.com/my_weblog/rasterdesign/

 

I hope this helps you.

Phil

 



Phil Borycens
Valued Mentor
parkr4st
Posts: 449
Registered: ‎03-24-2004
Message 4 of 11 (726 Views)

Re: Mr Sid image shifted 30 ft north

07-12-2012 03:04 AM in reply to: lorrie.bundy

what is the coordinate system of the MrSID?  What is the resolution of the photo?  What is the index point of the photo?  Do you need the entire photo for your current project?

 

Dve

Contributor
lorrie.bundy
Posts: 19
Registered: ‎02-24-2003
Message 5 of 11 (716 Views)

Re: Mr Sid image shifted 30 ft north

07-13-2012 10:41 AM in reply to: phil_borycens
Thank you for your reply. My question is clearly answered by you: "it seems that the conversion you are referring to is hard-coded in the program". Knowing this, I can move forward with a workaround. My chosen workaround is to create a dwg with sid inserted using MAPIINSERT where I entered sft conversion instead of using default conversion. My template xrefs this dwg for a base map. This way it doesn't matter what part of the county my project is located, I always have access to the base map without a large file size. 1. MAPIINSERT: I think providing the option for INTL or SURVEY ft unit conversion is a useful improvement. 2. My goal is to streamline workflow by having a template base map with topo and ortho of county since this is my service area. I want to avoid clipping images for work area since it takes time for this repetitive task and my experience is that the quality of the image is reduced. 3. To reproduce the exact issue....but I won't try the ftp since the sid I have is so large... a. create a dwg with UTM coord system and sft units b. Use MAPIINSERT to insert a sid image with source UTM coord system and mtr units. c. Select mtr for source units. d. Now use Map | Import to import a shapefile with source UTM coord system and mtr units. e. The sid image will be shifted 2 ppm compared to shapefile placement due to use of conversion factor applied to sid not being sft. f. For my situation, Northing (ft) is 15 million. So the shift is 30 ft. 4. The computer system is controlled by government purchasing and has less than 2 GB RAM. No plans for upgrading in the near future, so I am not able to try this option. 5. I will consider scale 1:1 as an option. Thank you again for helping with this!! My question is answered, but I'd love to hear if you have other tips. */\_____________________//\______________ Lorrie Bundy, PE NRCS 215 Executive Court, Suite A Yreka, CA 96097 (530) 842-6123 x.139 (530) 842-1027 fax This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately.
Contributor
lorrie.bundy
Posts: 19
Registered: ‎02-24-2003
Message 6 of 11 (715 Views)

Re: Mr Sid image shifted 30 ft north

07-13-2012 10:59 AM in reply to: parkr4st
Hi Dve, 1. Coordinate system of MrSid is UTM, distance meter. The dwg is UTM, distance sft. 2. Resolution of image is 1 meter (for example 2010 NAIP) 3. Index point....there are several since I am developing a library of dwgs, each dwg to contain 1 sid image to be xref as needed. There are 2 images to cover county, and 4 separate flight years. The template will have 1 xref then others can be xref as needed. Maybe you ask to get an idea of the error........The N is around 15 million, E around 1.6 million. Conversion using intl ft instead of sft results in 2 ppm difference, or 30 ft N for my area. 4. Yes I need the entire image for the project. As mentioned above, I am creating a library of images. My workaround is to use MAPIINSERT but enter the sft conversion instead of accepting the default. I understand that the default conversion is hardwired into the software, so I will continue entering the conversion factor. Thanks for your reply. */\_____________________//\______________ Lorrie Bundy, PE NRCS 215 Executive Court, Suite A Yreka, CA 96097 (530) 842-6123 x.139 (530) 842-1027 fax This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately.
Valued Mentor
parkr4st
Posts: 449
Registered: ‎03-24-2004
Message 7 of 11 (713 Views)

Re: Mr Sid image shifted 30 ft north

07-13-2012 11:36 AM in reply to: lorrie.bundy

lorrie

 

your coord system should be such as utm83-(Zone).  ie I use utm83-19 in the NE USA.  The local NRCS naip photos are either the same or state plane depending on which state.  open the corresponing .sdw file.  the last two lines are the e & n for the index point for that photo.  Usually center of top left pixel.  New drawing and set the coord system to the same as the phot, insert the photo.   Does that point fall onto the map at the correct coordinates?  that may account for your 30 feet of shift against a ground based control point.

 

Dave

Contributor
lorrie.bundy
Posts: 19
Registered: ‎02-24-2003
Message 8 of 11 (710 Views)

Re: Mr Sid image shifted 30 ft north

07-13-2012 01:46 PM in reply to: parkr4st
Hi Dave, Thank you for this suggestion. I investigated this and seem to have another problem. Maybe MAPIINSERT is not using sdw for insertion point? The X,Y coordinates from sdw file did not match insertion point values. 1. Contents from sdw file. 1.000000000000000 0.000000000000000 0.000000000000000 -1.000000000000000 437100.500000000000000 4657566.500000000000000 2. Here is screen shot of MAPIINSERT. DWG set to UTM83Z10sft. Image Source is UTM83Z10meter. Same X, Y if correlation source if World or Image. [cid:image003.png@01CD60F9.41FE9920] SO....If I ignore the discrepancy between the sdw coordinates and the insertion point values....the point I thought I was making is clear, and outlined below.... CAD harvests these source coordinates from somewhere (maybe not sdw) Select units "meters" for source units since they reflect meters.... [cid:image003.png@01CD60F9.41FE9920] Let CAD apply default conversion factor to source coordinates to find insertion points. [cid:image002.png@01CD60F8.1C2C3EB0] Simple calc to determine the conversion used Source / Insertion = conversion X: 437100 / 1434055.118 = 0.3048 Y: 4531519 / 1486788.32 = 0.3048 This is NOT the conversion factor shown in Toolspace / Edit Dwg Settings / Units and Zone. The conversion should be survey ft. [cid:image004.png@01CD60FD.E0F11220][cid:image005.png@01CD60FD.E0F11220] So I assume MAPIINSERT does not use the dwg setting to convert units, even though "Set AutoCAD variables to match" is selected. I was hoping to find out how to change the conversion value. MAPIINSERT does not provide the user with option for survey ft conversion. It assumes international ft. If I used more precise conversion by manually entering a scale (3.280833333), the insertion point changes as does the scaling and my image matches the position of the shapefiles imported using Map | Tools | Import. I noticed the difference between international feet and survey feet conversion is 2 ppm, or in my case since Northing is 15million, approx. 30 ft shift. I was hoping to find how to change the default conversion value so I wouldn't have to manually enter the scale, and I would be able to control the conversion value so all imported images use survey ft conversion. Obviously this only matters for large coordinate value conversions. Another Autodesk respondor indicated that this conversion value was not changeable. Hopefully this clarifies my issue. I really appreciate your suggestion since it made me consider another source of error. Please advise if you have any other suggestions. Thanks again. */\_____________________//\______________ Lorrie Bundy, PE NRCS 215 Executive Court, Suite A Yreka, CA 96097 (530) 842-6123 x.139 (530) 842-1027 fax This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately.
Valued Contributor
MATRIX3DSURVEYS
Posts: 98
Registered: ‎08-18-2005
Message 9 of 11 (699 Views)

Re: Mr Sid image shifted 30 ft north

07-15-2012 02:41 PM in reply to: lorrie.bundy

 

Note the abstract from a USDA SID file above a 3.75"x3.75" quarter quad is rectified to +/- 6 meters (19.68 feet) a county mosaic is composed of thousands of DOQQ's  which are then compressed in the SID format. At best a large area 1 meter SID has a Hz accuracy of +-10m but probably closer to 20m.  A 1 meter DOQQ has 1 meter pixels so the smallest discernible object contains at least 10 pixels. The rectification is to +/-6 meters so the point is somewhere inside a circle that is 12 meters in diameter.

In addition to this every time the image is re-projected more distortion is added.

 

Would suggest the following work flow.

 

Check the Meta data for the SID. Create a Drawing in that coordinate system. UTM 83-10 meters. Insert the SID with Raster Design.

Image > Insert >Insertion Dialog > Open >Source >World File Correlation > Apply > OK  

Save and Close the Drawing.

 

As a location check Create a Drawing in UTM 27-10 meters and import a DRG Topographic map with the collars. Set the system variable GEOLATLONGFORMAT to 1 (DMS) Set Drawing coordinates in lower left hand corner to Geographic.  Check the coordinates of the corners of the topo.    

 

Create a new drawing in required project coordinate system UTM83-10F  feet or local State Plane Coordinate System. (Toolspace>Settings Tab> Drawing Settings)

Go to Task Pane > Map Explorer > Attach Drawing with image file. Click current drawing and set coordinate systems for both current drawing and source drawing.

Define Query > Query (ALL/Layer) > Draw

 

Repeat above steps to import  the Topographic map. Set transparency and check against Aerial photo. Check Geographic Coordinates of corners.  

 

Detach the Source Drawings and save the New Work Drawing.

 

This method does not corrupt the source image file or rewrite the correlation files.

 

If more accurate correlation is required the photo can be matched to Surveyed Hard points using Match and Rubber Sheet commands on the Raster tools menu.  This is how the original  Images were Correlated in the first place.  

 

Remember GIS stands for GUESS INSTEAD of SURVEY.

 

Jim

Matrix3Dsurveys

 

 

Distinguished Contributor
cjneper
Posts: 128
Registered: ‎11-13-2006
Message 10 of 11 (681 Views)

Re: Mr Sid image shifted 30 ft north

07-17-2012 06:36 AM in reply to: lorrie.bundy

Mapiinsert frustrated me to the point that I wrote a lisp program to insert images instead... see attached.  This works for TIF images, not sure if SID images are different.  You will need to revise the program obviously to fit your directories and images, but this solved the problem for me.

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