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Cadastral Map issues: CAD to GIS

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#1
elib

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Dear members;

I am new to this forum and found it very useful while I was searching for some answers to my CAD - GIS problem. Thank you for all your efforts, and I hope someone can help me.

I have a CAD file, an cadastral map with no georeferencing, and I need to migrate it to ArcMap where I want to georeference it and move on with working with it from there.

What I have done up to now is that using coordinates of points from google earth, I was able to georeference the file


My problems are:
1- Is there a better way approach the georefrencing since I am only allowed to use two control points in ARCmap when dealing with CAD? Two points are not enough at all for my data. I did several trials and I am still not set for this referencing..

2- Assuming the georeferencing is fine. How shall I proceed? What I have now is polylines (which I can convert to polygons - representing parcels). How can I import the annotation, i.e. parcel number from autocad to GIS?


Is there actually a better way to do all of this? Am I thinking about this whole thing in a wrong way?

I really hope someone can help me!
I thank you in advance.

#2
French cartographer

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Dear members;

I am new to this forum and found it very useful while I was searching for some answers to my CAD - GIS problem. Thank you for all your efforts, and I hope someone can help me.

I have a CAD file, an cadastral map with no georeferencing, and I need to migrate it to ArcMap where I want to georeference it and move on with working with it from there.

What I have done up to now is that using coordinates of points from google earth, I was able to georeference the file


My problems are:
1- Is there a better way approach the georefrencing since I am only allowed to use two control points in ARCmap when dealing with CAD? Two points are not enough at all for my data. I did several trials and I am still not set for this referencing..

2- Assuming the georeferencing is fine. How shall I proceed? What I have now is polylines (which I can convert to polygons - representing parcels). How can I import the annotation, i.e. parcel number from autocad to GIS?


Is there actually a better way to do all of this? Am I thinking about this whole thing in a wrong way?

I really hope someone can help me!
I thank you in advance.


Hi from Paris :D ,

Concerning the first problem, maybe you should use the spatial ajustment toolbar in ArcMap, you'll find it many options to ajust your data.

For your second problem, two things:
a) If you want to convert polylines to polygons, i think you have to obtain ArcInfo (ArcGIS for Desktop Advanced). If ArcInfo is too expensive for you, you should use other software like QGIS (Quantum GIS) or ArcGIS extensions like ET GeoWizards(free).

B) To import CAD annotations from CAD like AutoCad or Microstation to ArcMap, use the ArcToolBox ( a tool called " " in ArcGIS 10 for example -ArcToolBox > Conversion Tool > To GeoDatabase > Import DAO anno.). If you use ESRI Geodatabase - Personal or File - you'll find many options to convert annotations.

Good luck ! :D

Best Regards from Paris

CartoExpert Formation SIG

#3
elib

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Hello from Byblos :)

Thank you so much for your help. I was able to register the map and then modify it with the spatial adjustment toolbar, and then transform my polylines to polygons.

Regarding the annotation issue, I am trying a few ways but I am not sure how I should approach this issue.

So, now, I have a registered cadastral map of polygons. I have another cad file with the annotation. I am able to import it using your advice. But, how do i link each parcel number to its corresponding parcel?


Should I have used from the beginning one file with the Cad parcels + Annotations?

#4
elib

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Finally, I have been able to transform my data.
Here is what I have done, in case someone might find this useful.

1- I cleaned up my cad file to have only annotations + parcels
2- I opened the cad file in ArcMap
3- I did a preliminary georeferencing of the file using two points I obtained from Google Earth (we can only use two control points with cad)
4- I used Data Management Tools > Features > Feature to Polygon. There I chose to use my polyline layer of CAD, and underneath there is a wonderful optional field "Label features". In this field, I chose the annotations to be my labels. Now I have a polygons as features with annotations! Beautiful!
5- I used the Editor and spatial adjustment toolbars to modify the map due to the weak georeferencing I already had with 2 control points. I did that using more points I obtained from google earth.

Great!

Next challenge:

There are duplicate parcel numbers because the same number can be used in different districts of a city. How shall I handle that?

How can I identify each district (e.g. using another map or geographical coordinates) in an easy and smart way? Then I can maybe add a new attribute for each district...

Does anyone have any ideas?

I would appreciate your help.


#5
Lego

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Finally, I have been able to transform my data.
Here is what I have done, in case someone might find this useful.

1- I cleaned up my cad file to have only annotations + parcels
2- I opened the cad file in ArcMap
3- I did a preliminary georeferencing of the file using two points I obtained from Google Earth (we can only use two control points with cad)
4- I used Data Management Tools > Features > Feature to Polygon. There I chose to use my polyline layer of CAD, and underneath there is a wonderful optional field "Label features". In this field, I chose the annotations to be my labels. Now I have a polygons as features with annotations! Beautiful!
5- I used the Editor and spatial adjustment toolbars to modify the map due to the weak georeferencing I already had with 2 control points. I did that using more points I obtained from google earth.

Great!

Next challenge:

There are duplicate parcel numbers because the same number can be used in different districts of a city. How shall I handle that?

How can I identify each district (e.g. using another map or geographical coordinates) in an easy and smart way? Then I can maybe add a new attribute for each district...

Does anyone have any ideas?

I would appreciate your help.


Elib thanx alot for this post, it has helped me figure out some questions i had concerning CAD-GIS issues. so for the issue of duplicate parcel numbers, i would suggest you use composite identifying queries e.g. something like "[parcel no.]='04' AND [district]='Kampala'

#6
Bilal

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Finally, I have been able to transform my data.
Here is what I have done, in case someone might find this useful.

1- I cleaned up my cad file to have only annotations + parcels
2- I opened the cad file in ArcMap
3- I did a preliminary georeferencing of the file using two points I obtained from Google Earth (we can only use two control points with cad)
4- I used Data Management Tools > Features > Feature to Polygon. There I chose to use my polyline layer of CAD, and underneath there is a wonderful optional field "Label features". In this field, I chose the annotations to be my labels. Now I have a polygons as features with annotations! Beautiful!
5- I used the Editor and spatial adjustment toolbars to modify the map due to the weak georeferencing I already had with 2 control points. I did that using more points I obtained from google earth.

Great!

Next challenge:

There are duplicate parcel numbers because the same number can be used in different districts of a city. How shall I handle that?

How can I identify each district (e.g. using another map or geographical coordinates) in an easy and smart way? Then I can maybe add a new attribute for each district...

Does anyone have any ideas?

I would appreciate your help.


Elib thanx alot for this post, it has helped me figure out some questions i had concerning CAD-GIS issues. so for the issue of duplicate parcel numbers, i would suggest you use composite identifying queries e.g. something like "[parcel no.]='04' AND [district]='Kampala'

if i got it well, you need a district name map then ---> identity fuction between parcels and district name then you will solve the duplicated issue it's ordinay to have such aduplicate if u have more than one block

www.ramallah-gis .ps

#7
elib

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Thank you Lego and Bilal for your help. I finally managed to work out this issue.

#8
Kalai Selvan

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Hi Elib,

Glad that you found out the solution for your issue, i feel its a way too long process what you have been doing.

1.Since, you had non georeferenced data in cad file.There is a option called Rubbersheeting option in autocad, which can handle any number of control points for transformation.

That could have solved your 2 point option of georeferencing.

And other things like annotation and duplicate cleanup, is right what you been doing in arcmap.

Hope that helps in future..

Thanks and Regards
Kalai Selvan





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