Looking For A Roller Scanner In Chiang Mai To Scan A1 Sized Image
9 replies to this topic
Posted 2010-09-10 16:40:45
Anyone know of somewhere in Chiang Mai that either has a good quality roller scanner (scanner that rolls the paper image through it). I want to scan a number of maps - the military maps as mentioned here. (The reason I want to scan them is then I can use them with my GPS equipment to plot my current track in real time on the map).
The Royal Thai Survey Department sells these paper maps and also sells scanned versions of them but the scanned versions are not scanned at a high enough resolution to see clearly all the details on the maps. They are scanned at roughly 240 dpi whereas a good modern scanner should do 300 - 600 dpi.
Have already tried the copy shop next to the 7-11 North of the three king's monument which several people have referred me too. This seems to be the most well known shop in town for this type of thing. But there scanner is around 15 years old and the resolution and contrast of the scanned image is very poor.
Other methods to digitize the maps might be to have a set up to take a digital pic of the maps with a special tripod to hold a digital camera over the maps. Or maybe I will cut the maps into sections and then scan the sections of the map. A shop that has a good quality A2 scanner would be useful. A3 scanners seem pretty common.
Posted 2010-09-11 22:00:23
Have you bought one of the scanned images? It's been a while since I did any scanning, but I would have thought 240dpi was good enough for printing a paper copy, let alone viewing on a handheld gps. Do you know if it's possible to buy the scanned copies online?
Posted 2010-09-12 17:31:52
I bought the scanned image of the map of Chiang Mai and the Pui / Suthep National Park 4746 I.
Actually the only problem I have is the Thai script on the map is very difficult to read. The Thai names of villages and other places are in a smaller font than the English names. They are mostly legible if you strain your eyes. But would be nice if I could zoom in to read the names. Have learned to read Thai and reading the names in Thai and getting the pronunciation right I think is a lot easier than try to guess at the pronunciation when the word is written in English. Also would be nice if the map image was crisper and less blurred at high zoom levels. Have a nice GPS set up on my Nokia N97 smart phone which has a big color touch screen.
Am a very dedicated hiker and will continue my search to be able to scan at a higher resolution, although the images from the RTSD would be usable for my purposes as well. Have an A4 scanner at home and scanned a portion of a map at 600 dpi and they looked great!
Really I don't know why the RTSD is not able to create images directly from their mapping software at high resolution rather than printing and then scanning the result which seems ass backwards to me.
I do not know if the maps are available online. When searching for the contact info for the RTSD this time around though I did come across an ecommerce site offering maps for sale, possibly the RTSD's own site. Have not found it since and the whole RTSD web site was down for some time but just recently seems to have reappeared.
Posted 2010-09-12 21:28:51
How does the sample map jpeg on your website compare with the one you bought. Looks pretty washed out & compressed. What kind of file did you buy & how large? I would like to buy one for San Kampheang area, but not if it's so compressed.
Posted 2010-09-13 06:58:52
The image I had up on the web site before was from my attempt at scanning the map myself at the shop near the 3 King's Monument in town with the antiquated printer.
I have put up new images on the web site here : http://cmhike.com/20...-been-released/ These are sections of the scanned map as supplied by the RTSD before and after using auto levels in Photo shop.
If you have any knowledge of scanning and image processing some comments about where they might of gone wrong in scanning and how to improve the quality of the image would be much appreciated! I think they used a lossless compression ie. 100% quality compression algorithm - lza.
Posted 2010-09-13 07:49:03
The scanned image I bought was supplied as a 38.1 MB tif file. Dimensions 5648 by 6891 with just 8 bit depth for colors. Just checked and it appears to be completely uncompressed, not using any compression at all.
Posted 2010-09-13 13:10:06
How does the detail & text look in the original tif file? If that is good, maybe your problem occurs when you save as jpeg? Can you post a sample saved in the original tif format, without any compression?
Posted 2010-09-13 15:33:35
Here is a screen shot of the original tif file that RTSD supplied (on the left) and a 600 dpi image that I scanned myself side by side. You will notice that some of the roads are different or do not exist on the blurred file RTSD supplied, they sent me an old version of the map from 1999 rather than the latest 2007 print.
sidebyside.JPG 282.65K 23 downloads
Edited by jamiesensei, 2010-09-13 15:47:06.
Posted 2010-09-14 19:22:39
I would need to take several shots (to get a resolution of 600 dpi of an A1 map that is 33.1 * 23.4 inches it will have a total pixel count of 278834400 ie around 279 Mega Pixels) and then stitch them together somehow which I would imagine would be a pain and might result in some slight shifts in the image coordinates which would then make the resulting map less accurate for gps purposes.