tiff versus jpeg files - ortophoto images

Hello everybody,

I work with autocad map 2008, and my company use drawings with 20-30 tiffs (aerial views - ortophotoimages), each of them about 70-80 MB size.

I use 1 layer for 4 tiffs, to work easy. After inserting this ortophoto images in autocad drawings, i converted this huge tiff files into jpeg files, then insert this new jpeg files to their correct position (put above tiff files), and then i erased all tiff files. So, finally, i work with jpeg files (about 5 MB each ortophotoplan), and i can say the quality of this jpeg files is ok. Does anybody know if there are any problems caused by jpeg files? do you think is ok what i'm doing? Any sugestion of indication is ok for me, please tell me other way of working with lots of huge tiffs, or help me with any idea.

Thanks!

base on your explanation it sounds like you have the right idea. Tiffs are generally smaller and easier to deal with than jpegs in my travels (the plotter usually takes longer to process the jpegs). the tiffs i usually make transparent and i turn off the image while i don't need it at the moment. But in your case I'd say that doesn't matter unless your getting some major lag in your machine. Mine would have some problems with that.

base on your explanation it sounds like you have the right idea. Tiffs are generally smaller and easier to deal with than jpegs in my travels (the plotter usually takes longer to process the jpegs). the tiffs i usually make transparent and i turn off the image while i don't need it at the moment. But in your case I'd say that doesn't matter unless your getting some major lag in your machine. Mine would have some problems with that.

I don't know how you say that jpegs are bigger than tiffs, in my case i made jpegs of about 5 mb from original tiffs that were 70-80 mb, and the quality is about the same (looks the same). Is it true that the plotter need a longer time to process a jpeg than a tiff? Thanks!

I don't know how you say that jpegs are bigger than tiffs, in my case i made jpegs of about 5 mb from original tiffs that were 70-80 mb, and the quality is about the same (looks the same). Is it true that the plotter need a longer time to process a jpeg than a tiff? Thanks!

Thats just in my expeirence. But keep in mind i usually lower the color count to about 2 (1bit) and trasparent for tracings and figures. The jpegs i'll use for usgs and vicinity maps. all things considered i don't deal with anything close the the sizes you work with.

Thats just in my expeirence. But keep in mind i usually lower the color count to about 2 (1bit) and trasparent for tracings and figures. The jpegs i'll use for usgs and vicinity maps. all things considered i don't deal with anything close the the sizes you work with.

The good thing about jpgs, is that they can be compressed. The bad thing is that it is a lossy format. If you are using aerial photos, at least for presentation type graphics, you would probably want to keep the color.

HTH,

Ray

Jpeg is know as lossy format, in compressing it looses data and sometimes the images appear 'dirty', for arieal photos, this is not normally a problem. If you are using TIF, I would use a compressed version, LZW is good. There is a great free utility Irfanview which is excellent at batch converting files, you can use it to resize, reduce colours and a lot more.

The better formats for Aerial photos are ECW or Mr Sid, you can view these in Map, but you will need to download the free raster design object enabler from the Autodesk web site.

The problem with these formats is you need specialist conversion software that embeds location information in the files, but done right you can use one image for all you data and it works really well.

Gary,

I run RasterDesign on top of Map . I have been trying to drag n' drop jpg and tif aerial photos of a mine site with no luck. They have world files defined. I have no problem with ESRI shp files and dwgs. Would the ECW or Mr Sid format work better?

Gary,

 

I run RasterDesign on top of Map . I have been trying to drag n' drop jpg and tif aerial photos of a mine site with no luck. They have world files defined. I have no problem with ESRI shp files and dwgs. Would the ECW or Mr Sid format work better?

I can't comment too much about drag and drop of images, I'm not 100% sure what handler code will take control.

Normally the problem with inserting images with world files are units.

If you are using map, just use the Map > Image > insert command

Then leave the units at default, the units here represent the dots per unit in the image not the units being used in your drawing. What problems are you seeing?

But to answer you question, I've (this is not to say they don't) never seen a ECW come into the wrong place, assuming units and projecttions are correct. So if you have a choice or chance of using ECW try them

Regards

Gary