Adelaide Panorama
A comment was made to me a few months ago about my photoblog - It is called "Adelaide thru my lens" yet has hardly any pictures of Adelaide in it! On reflection the comment was correct. So today, I went out and rectified that!
A few days ago, I came across a little lookout that is about 8km Due east of the city and around 600 or so Metres high. I took a series of photos from there and created a pano of the cityscape.
Ok, Now on to the nitty gritty about the pictures.
I took around 60 photos from the lookout across the city - some were wide-angle shots and I also did 2 series of pictures that I could look at using to create Panorama pictures from.
The series I decided to use were all shot handheld in portrait mode - 1/320 sec, 100 ISO at 200mm (400mm equiv 35mm film format). I used 8 pictures with varying amounts of overlap and put together a very large picture.
I posted a very small version in my photoblog of the completed image.
To put together a decent Pano it takes quite a bit of effort in the Processing to get to the end result. And this is how I processed the 8 individual images and created the end product.
Firstly, I processed the RAW images in Rawshooter Premium making some very small corrections. Then, I saved them as 8bit tif files at 156% (upsizing them). You may wonder why I up-sized them and the reason is simple - From past experience, I have found I can better optimise the end picture by upsizing from RAW and then down-sizing and sharpening towards the end of the process. I chose this size for a couple of reasons - I ended up with tif images 3898x5203pixels and 58Meg each file.
This gave me a lot of image to deal with and plenty of scope to crop as required once I stitched the images together.
Now, a quick look over the 8 tif images indicated I had no problems - so on to the stitching. In the past, I have created pano's from jpg files and let autostitch do the work of joining them all up, but this time, I tried some other software that in the past I had not had a lot of success with. I used Hugin to stitch the images together.
Hugin gives you incredible control over the whole stitching process as you need to set up a lot of info so you can let it do it's job. Firstly, you select the images that you want to stitch together. then, you set up some parameters regarding the lens you used to take the pictures. Step 3 is the most important bit - you set the control points.
The control points are simply points that are common between image 1 and image 2 - so that they can be joined together. Step 4 is the optomiser - I just used the auto process and let it do it's thing. and finally step 5 - the stitcher process. This is where you set the parameters to join the photos together. I found that it is important to do a preview at this stage in order to ensure everything is reasonably ok - and to ensure that the Field of view is correctly set.
Once the FOV is ok and the preview looks right, then set the output parameters and let it go!
I wanted a full-sized tif image for the output as I knew I still had more processing that would need to be done before I finished. So, I clicked on stitch and let it go for the next 10 minutes or so.
Once It was stitched, then the next thing to do was to open up the image and inspect it. The resultant image is a very large file at this stage - I have a 470Meg Tif image that is 21768x5670 pixels in size (or a 127Megapixel Image!) So, I opened up the Gimp and loaded the picture. I set the image to 200% so I could browse the whole image and carefully inspected it especially where the joins were. And as luck would have it - I could see 4 joins in the image.
Now, I had to go and take a look at why - and I went back to Hugin. In my haste, I had only set about 3 or 4 control points between each image. So, I took a bit more time and actually set between 12 and 15 control points between each image. Then I re-did what I had done before and produced another stitched picture.
Again, I went and looked at the stitched image at 200% in the Gimp and was much happier! I searched and searched and only found 1 very small area where there was any visible join. As it was so minor I decided that further processing was not really required. and I was ready to move onto the next step which was to crop the image off where the jagged edges were due to the variations in the pictures.
So, in the Gimp, I carefully looked at every side of the image and found I could crop out an area of 17930 x 3870. Once cropped, I saved out the tif image ready for further processing. At this stage I have a 264Meg - 69Megapixel file.
During the processing steps I have noted that there is a small amount of noise in the image, so the next trick is to open up noiseware. Now I use the Standard edition as the free community edition cannot work with tif files. The image only has a small amount of noise, so I selected a profile that would only remove a small amount of noise. At the same time, I chose to apply a +1 sharpening to the image. After processing and checking, the noise had been reduced to an acceptable level and there were no obvious problems introduced. Finally saving out the processed image again as a tif. The file was now just a bit smaller at 198Meg. The reduced file size was as a result of removing the noise - and of course some of the detail as well.
Well, at this point I have what I refer to as my "Negative" - A high quality image that is ready for me to resize as required.
The final step for me to get from the 198Meg file to the 156K jpg that I posted to my Blog was to load the image back into the Gimp and do the resizing and save as.
You might wonder why I went to all the trouble to generate a photo that covers only 21deg (W) by 5.6deg (H) - I could have done the same thing by taking a single photo at around 65mm focal length and cropping a bit off the top and bottom. I would have been able to get an Identical sized image that would be suitable to post to my blog.
BUT, Had I done this with a single photo the largest possible size I could expect to print would be about 4" x 10" and be approx 4 Megapixels in size. Instead, I have a picture that If I wanted to, I could print out at a massive 15 1/2 inches by 72 Inches in size, Remember, I have a whole 69Megapixels to play with.
Of course, the Image I posted to my blog does not look too spectacular, but the full-sized image is pretty impressive to say the least.
