10 replies to this topic

[oombaca]

HI,

I have a large database created in the eighties (by what looks like MicroStation or CAD of some other sort) of TEK species landuse data. It is now in shapefile format, however it consist entirely of lines which are intended to represent both area and linear landuse.

I've come up with a way of extracting the intended polygon data into a separate shapefile using a series of steps with ET Geowizard.

Extracting the line data is proving more vexing. The size of the database makes visually selecting and extracting them impractical (over 7000 objects times 15 communities) and the polygons I've created from the "line polygons" are not an exact match to the original lines so selecting by matching them and switching doesn't work.

Any ideas about methodology or software that could help?

I'm using the basic ArcView license with no extensions.

The above is (hopefully) all you need about the practical side of this problem. If you're interested there's some background information below. It should explain why I think this project is important.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I've been asked to make a land-use atlas for an indigenous community based on traditional ecological knowledge collected in the late 70s as a baseline for further data collection.

As I explored the data I realized 3 things: 1) this data represented 100s, maybe 1000s of hours of field work and depicted TEK (tradional ecological knowledge) from as far back as the 30s described temporally as well as geographically, 2) it was locked away in a format that made it mostly useless to their regional government and 3) the value of what was locked away was immense with respect to any land management decisions (treaty rights, land negotiations, impact assessments etc) not to mention the cultural heritage element which is hard to underrate.

Although my project involves only one community the entire database covers 15. I want to find a way to set this data free for use by their regional government.

My mission then would be convert all the intended polygons to actual polygons in a separate shapefile and extract the intended lines to a new shapefile of their own all with their attribute data still attached, however the budget is limited as the the regional government has limited resources and a lot to deal with.

Thanks for any ideas or suggestions!

[Hans van der Maarel]

I think I know the answer to this one already, but I'll ask anyway...

Is there any way you can get hold of the original data (i.e. in the format it was in before it was converted to shapefile)? There might be a layering structure there that didn't carry over properly to shapefile. If so, that might be an easy clue as to where the lines are.

Alternatively, can you share the file here so that we can have a look?

[Gretchen Peterson]

How close together are the polygons and lines? You mentioned that you can't do an exact Select By Location, Are Identical To, but I wonder if you could use Select By Location, Are Within Distance Of and apply a buffer to the features of some amount. This may allow you to select the majority of the polygon lines. With the remaining data you can do a Switch Selection and make a shapefile out of the lines then compare the two datasets up close and manually delete the polygons that accidentally were selected. For on-screen editing always draw a box (Drawing Tool) around the spots that you've inspected so that you do not go over them more than once.

[Jimbo]

Check to see if there is a column type under Geometry type & if there is you should be able to select by polyline, polygons, & points.

[ProMapper]

I think I know the answer to this one already, but I'll ask anyway...

Is there any way you can get hold of the original data (i.e. in the format it was in before it was converted to shapefile)? There might be a layering structure there that didn't carry over properly to shapefile. If so, that might be an easy clue as to where the lines are.

Alternatively, can you share the file here so that we can have a look?

Hans is correct there, Microstation file has a layered structure and the older versions had only 64 layers. Along with that CAD also supports element color, style, type and other attributes which are discarded when exported to Arc or other GIS formats. So it is essential to get the original data for correctly exporting it.

[oombaca]

I think I know the answer to this one already, but I'll ask anyway...

Is there any way you can get hold of the original data (i.e. in the format it was in before it was converted to shapefile)? There might be a layering structure there that didn't carry over properly to shapefile. If so, that might be an easy clue as to where the lines are.

Alternatively, can you share the file here so that we can have a look?

I'll check, but I don't believe I can get the original files. I do have access to the original field maps. I'll check about that this week and get back to you.

I'll also check about sharing the file however I doubt I'd be allowed, I might be able to extract a sample if that's any use.

[oombaca]

How close together are the polygons and lines? You mentioned that you can't do an exact Select By Location, Are Identical To, but I wonder if you could use Select By Location, Are Within Distance Of and apply a buffer to the features of some amount. This may allow you to select the majority of the polygon lines. With the remaining data you can do a Switch Selection and make a shapefile out of the lines then compare the two datasets up close and manually delete the polygons that accidentally were selected. For on-screen editing always draw a box (Drawing Tool) around the spots that you've inspected so that you do not go over them more than once.

The lines and polygons do over lap quite a bit. The data is the compiled results of many field interviews of hunters using the same area so, as is, the data resembles a "spaghtetti map" useful for expressing intensity of land use by the community but little else and even then, with respect to more important resources, the data just obscures itself.

I did tried a basic select using a buffer but ran into trouble getting it to work right. You've inspired to give it another shot though: I'll let you know how it goes.

[oombaca]

Check to see if there is a column type under Geometry type & if there is you should be able to select by polyline, polygons, & points.

No such luck!
That would have been great.

I also want to say thanks to everyone for the quick and helpful responses!

[oombaca]

Just to keep you updated, I've tracked down a copy of the original files but they are on some old storage mediums I need to get around. My boss muttered something about a jazz drive. I've had to switch focuses temporarily but will keep you posted as things evolve.

[Hans van der Maarel]

Just to keep you updated, I've tracked down a copy of the original files but they are on some old storage mediums I need to get around. My boss muttered something about a jazz drive. I've had to switch focuses temporarily but will keep you posted as things evolve.

I remember Jaz-drives! Stored a whopping 1 Gb...

[imran aziz tunio]

I also want to say thanks to everyone for the quick and helpful responses!

Edited by frax, 29 November 2010 - 03:45 AM.
removed unformatted quote