geo-referencing

[Adventure Mapper]

Sometimes the only way to get information is on a paper map or simple .jpg or .pdf. In this case it is necessary to geo-reference the map. This involves selecting points on the map to be geo-referenced where the latitude and longitude are known. The attached map of roads in the Coast Range was PhotoShopped so that white space could be made transparent, geo-referenced, and converted to .kmz. Coast Range roads are often gated, permanently blocked, or impassable. This map is quite accurate and up-to-date so I was able to know the best way to the Sawtooth Range. It also shows the places where there will be ORV traffic and big party oriented camp sites. The original map can be found here http://www.oregon.gov/odf/tillamookstat ... fohv09.pdf.

I use Global Mapper for geo-referencing. I know QGIS can be used and there are crude ways in Google Earth but I haven't tried these. I'm wondering if anyone knows a free and easy way of geo-referencing.

A reminder that you can sign up for "Cartography for Wilderness Exploration" at PCC this January. http://www.pcc.edu/schedule/default.cfm ... topicCode=

[kepPNW]

I use Global Mapper for geo-referencing. I know QGIS can be used and there are crude ways in Google Earth but I haven't tried these. I'm wondering if anyone knows a free and easy way of geo-referencing.

Funny coincidence you write this up today. I whipped up this KMZ as a demo for someone else earlier this morning. That one started with this Tillamook State Forest PDF.

Yesterday, in another thread, I took a map drawn by Don Lowe back in the 80's, and did the same with it.

I just used Google Earth for both, which was quick and easy - and free. I can't really imagine a reason to use anything more complicated or expensive for most hand-drawn things like this.

[kepPNW]

Hmmmm, looking at your PDF, yeah, I now think it does need more than Google Earth. Seems some sheer needs to be applied, and that just isn't an option in GE. I could get it close at two opposite corners, but then the other two were out of whack. Funky projection, there.

[Lurch]

I appreciate your threads and all.. but I don't think it's an appropriate place to be advertising for your course. Especially since it isn't a free course.

[retired jerry]

Yeah, he's plugging his course, but

It is hiking related and a number of people have shown interest

He has also given useful information

I bet he isn't getting rich off it

[kepPNW]

I use Global Mapper for geo-referencing. I know QGIS can be used and there are crude ways in Google Earth but I haven't tried these. I'm wondering if anyone knows a free and easy way of geo-referencing.

I'm curious why you don't just use ArcMap for it? What advantages do you find with Global Mapper? I haven't used the latter, so I'm open to taking a look if it offers something ESRI doesn't.

I just georef'd your image using ArcMap 10.1, and arrived at a near-perfect fit. That image really needed some tweaking, though. I sense it may have been drafted from non-ortho aerial imagery. Simple transforms just weren't enough. Seemed I needed ArcMap to warp it a bit more. I'm not aware of free offerings that can do that, either.

[Adventure Mapper]

Hmmmm, looking at your PDF, yeah, I now think it does need more than Google Earth. Seems some sheer needs to be applied, and that just isn't an option in GE. I could get it close at two opposite corners, but then the other two were out of whack. Funky projection, there.

Google Earth expects everything to be right. Global Mapper and other GIS programs can use complex algorithms to essentially "rubber sheet" a distorted map. You are correct that most of the time this is not necessary.

Looks like you have a good collection of Lowe guides.

[Adventure Mapper]

[quote="kepPNWI'm curious why you don't just use ArcMap for it? What advantages do you find with Global Mapper? I haven't used the latter, so I'm open to taking a look if it offers something ESRI doesn't.[/quote]
I got started with Global Mapper before having access to ArcMap so I learned to like it. Also, I don't always have access to ArcMap. For some terrain processing like watershed and stream delineation ArcMap is better (although I understand new versions of Global Mapper have this capability). For other processing like viewsheds I like Global Mapper. The big problem with ArcMap for most folks is expense. As part of course preparation for a class I am teaching I should probaly check out QGIS. I was hoping someone out there had some expwerience with it.

[Adventure Mapper]

I appreciate your threads and all.. but I don't think it's an appropriate place to be advertising for your course. Especially since it isn't a free course.

Cartography and teaching are only retirement activities for me. It's a volunteer gig. It involves a lot of preparation as do some of my posts on Portland Hikers. Someone did request that I post a reminder. I think it is reasonable for PCC to charge a fee for the class since it uses their computer lab and requires Community Education staff support. Unless there are way more people signed up than I see so far I suspect that PCC will lose money on it.

I do hope to generate enough interest so that PCC will want to offer the class again (although I don't know why since it is a lot of work). I can see why we don't want ads for retail shops and such but I'm happy to learn about guidebooks from their authors, guided hikes (even with fees) from their leaders, and classes from their teachers.

In any case, in the future you'll need to look through the flyer you may get in the mail from PCC.

[kepPNW]

Google Earth expects everything to be right. Global Mapper and other GIS programs can use complex algorithms to essentially "rubber sheet" a distorted map. You are correct that most of the time this is not necessary.

Looks like you have a good collection of Lowe guides.

Yeah, if the original was based on something with reasonable accuracy, it'll get the job done pretty well. I just sorta stumbled into some of those old clippings. I think there are other boxes in the garage with some of the books in them. Kind of embarrassing to not know.

I got started with Global Mapper before having access to ArcMap so I learned to like it. Also, I don't always have access to ArcMap. For some terrain processing like watershed and stream delineation ArcMap is better (although I understand new versions of Global Mapper have this capability). For other processing like viewsheds I like Global Mapper. The big problem with ArcMap for most folks is expense. As part of course preparation for a class I am teaching I should probaly check out QGIS. I was hoping someone out there had some expwerience with it.

Ahhh, sure, I see. It's way out of reach for anyone to have for personal use. I'm lucky enough to have a license server on the network, so I can dabble. I assumed you were in a similar situation. And, I guess when you have that available, the impulse to check out some of these less costly alternatives is diminished a good bit. I've heard good things about QGIS, but no personal experience.