User talk:JimIrwin: Difference between revisions
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:Grass is forgiving with respect to camera parameters. I use rough estimates for the 9x9 images and 9x7 images. I use a 209.5 mm focal length, and {0,0} for the x,y point of symmetry. I use the inside corners or perforations of the 4 fiducial marks for the image-to-photo transformation. |
:Grass is forgiving with respect to camera parameters. I use rough estimates for the 9x9 images and 9x7 images. I use a 209.5 mm focal length, and {0,0} for the x,y point of symmetry. I use the inside corners or perforations of the 4 fiducial marks for the image-to-photo transformation. |
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<table border="1" cellpadding="4" cellspacing="0" style="margin-left:20px"> |
<table border="1" cellpadding="4" cellspacing="0" style="margin-left:20px"> |
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<tr><th>Parameter</th><th> |
<tr><th>Parameter</th><th> Images</th><th> Images</th></tr> |
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<tr><th>Focal Length mm.</th><td>209.55</td><td>209.5</td></tr> |
<tr><th>Focal Length mm.</th><td>209.55</td><td>209.5</td></tr> |
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<tr><th>X-coord.</th> <td>0</td> <td>0</td></tr> |
<tr><th>X-coord.</th> <td>0</td> <td>0</td></tr> |
Revision as of 14:24, 26 June 2012
I am also trying to connect Hoboken as the place where vagrants and others hopped on trains for free rides. They were called Hobos and I am trying to determine if the name "Hobo" was derived from the fact that rail transportation once originated and ended in Hoboken, and rail cars were then ferried over to Neww York City prior to the construction of railroad tunnels, hence the name " Hobo"
- Sorry, I have no information about the origin of the word "Hobo". There may be some online dictionaries that have the history.
- -- JimIrwin (talk) 13:44, 4 January 2009 (UTC)
Bergen Neck and Bergen Hill rail crossings
Thank you very much for your work regarding RR's in NJ. I wonder if you can help. I am trying to determine the dates, and names (official or colloquial) for all the crossings/cuts in Hudson County. Most difficult is to determine that used by Hudson Bergen Light Rail. Would be of great help. Djflem (talk) 18:53, 25 June 2009 (UTC)
Wilkes-Barre and Eastern RR
Hi JimIrwin:
I'm a GIS Analyst with Monroe County Planning Commission and am working on locating the abandoned rail ROWs in our county. Admittedly, there aren't a lot, but the WB&E and the NYS&W are of particular interest to me.
I'm wondering if you would be able to give me more information on your source material for the NYSW_Wilkes-Barre_and_Eastern.svg image you've created. I've developed what I feel is a pretty accurate location for the ROW by using scanned aerial photography from the late 1930s, but I wanted to compare it with other sources.
Thanks for time, and hope to hear from you.
George Basila
- George, I used historical USGS quads found on Maptech, combined with historical aerial photos from PennPilot, combined with current aerial photography from Google and Pennsylvania GIS. The historical USGS quads don't have good spatial quality, but they do provide a general route labeled with the railroad name. Using those as a starting point, I obtained the 1930's aerial photos from PennPilot and ortho-rectified them using GRASS, georeferenced to current aerial images from Microsoft Virtual Earth and using elevation data from the National Elevation Dataset. Once I had a continuous set of 1930 orthophotos, I digitized the route and created the maps.
- It was a lot of tedious work, but it sounds like you pretty much went with the same process. If you didn't orthorectify the aerial photos, I recommend that you don't rely on their spatial accuracy. In the high-relief terrain crossed by the WBE, the aerial photos can be off by quite a bit unless they are orthorectified.
- Jim Irwin (talk) 15:10, 28 October 2010 (UTC)
- Thanks for the info Jim! I didn't orthorectify the images, just georeferenced them in ArcMap. I'm using the 2005 PAMAP orthos as a base to digitize the ROW, with the PennPilot images as a reference. The areas on the aerial photos that don't warp to the orthos "fortunately" have the ROW visible on the PAMAP orthos.
- Do you mind if I ask, are you a GIS guy, or just get into this on your own?
- Nope, just an amateur, but I've been doing it for about 15 years now. Nowadays, I use Manifold and Adobe Illustrator for creating maps that interest me. I have GRASS just to do the orthorectification. When I first started playing with map datasets, I wrote my own software because I couldn't justify the cost of ArcMap. I still can't justify its cost!
- — Jim Irwin (talk) 19:55, 29 October 2010 (UTC)
Camera Info for penn pilot images
Jim, I want to try to orthorectify some of the 1938-40 penn pilot photos in GRASS. What camera parameters did you use? I have also been using the 3M (1/9 arc) digital elevation data for Ohio and Pennsylvania that recently became available. Many old rights of way are clearly visible.
- Grass is forgiving with respect to camera parameters. I use rough estimates for the 9x9 images and 9x7 images. I use a 209.5 mm focal length, and {0,0} for the x,y point of symmetry. I use the inside corners or perforations of the 4 fiducial marks for the image-to-photo transformation.
Parameter | 9x9 Images | 9x7 Images |
---|---|---|
Focal Length mm. | 209.55 | 209.5 |
X-coord. | 0 | 0 |
Y-COord | 0 | 0 |
Fiducial marks | 4 | 4 |
Fid#1 ID, Xf, Yf | top, 0, 110 | top, 0, 85.73 |
Fid#2 ID, Xf, Yf | right, 110, 0 | right, 111.13, 0 |
Fid#3 ID, Xf, Yf | bottom, 0, -110 | bottom, 0, -85.73 |
Fid#4 ID, Xf, Yf | left, -110, 0 | left, -111.13, 0 |