Frequently Asked Questions
Air Photo Search Questions
Q. How do I view information about an air photo in Google Earth?
A. Click the blue disk icon on top of an air photo centre to view information about that air photo. If a low-resolution version of the air photo is available it will be shown as a thumbnail image. Click on the thumbnail to view the low-resolution version of the image. If the air photo is available for purchase, an Add to Cart button will be displayed below the air photo details.
Q. Why do the low-resolution versions of some air photos seem to be upside down while others are right side up?
A. Because that's the way the photo appears on the film roll when they are scanned. Typically, flightlines are flown East-to-West and then West-to-East (or vice versa) in what is called a serpentine pattern. This results in half the photos appearing to have North at the top, and half with North at the bottom. Sometimes the aircraft fly in different patterns and the terrain features in the photos will appear to be rotated with respect to matching features in the Google Earth imagery. If you wish to compare features in the low-resolution images with those in Google Earth, simply rotate the Google Earth map to match the orientation of the photo.
Q. Why are there no low-resolution thumbnails for some air photos?
A. GeoBC has over 2.5 million air photos of British Columbia, dating back to 1936. To date only about 500,000 air photos have been scanned to digital format. Air photos that have not yet been scanned will not have a thumbnail image available.
Q. Why are the flight lines not shown like they are in the Airphoto Viewer or Base Map Online Store?
A. WIMSI shows you air photo centres from many years at once. Those applications only show you results for one year at a time. User testing revealed that showing flight lines from more than one year at a time was too confusing.
Q. Can I download and view or print the low-resolution image without purchasing the full-resolution version?
A. Yes. The low-resolution air photo images are free for personal use, although they reamin the copyrighted property of the Province of British Columbia. For commercial use, or for inclusion in published material you will need to get permission.
Q. How do I buy an Air Photo?
A. Click the Add to Cart button to add an air photo to the shopping cart for purchase.
Q. Are there other other air photos available for British Columbia?
A. Yes. This viewer only shows air photo centres back to 1963. To find older air photos, try the Air Photo Index Map search form. Additional advice for finding air photos from before 1963 can be found here.
Air Photo Index Map Search Questions
Q. How do I view the index maps?
A. The individual map icons will be labelled with the photo scale and range of years for those filmrolls represented on that map. Click the map icon for the scale and range of years in which you are interested to view information about that map. To view the map as an overlay directly in Google Earth, click the 'Show Map In Google Earth' link. To view the map in a separate window, click the 'Download PDF' link.
Hint: to better see the underlying terrain when viewing the maps as overlays in Google Earth, set the transparency slider for each layer to between 35 and 50%. You will be able to see the map annotations and the basic terrain features from the Google Earth imagery simulataneously.
Q. The overlay layers aren't displaying correctly in Google Earth - I'm only seeing the lower left quarter of the map.
A. Your graphics card doesn't have enough on board memory to support correct viewing of the overlay maps. Use the 'Download PDF' link to view the map in a separate browser window.
Q. How do I figure which air photo I want?
A. The index maps show flight lines, which are labelled with the filmroll name. Typically, the photo centre of the first and last photo in a filmroll and every tenth interevening photo are shown as a circles labelled inside with the frame number for that photo. Individual air photos are uniquely designated by the filmroll and the frame number. The locations of air photos that are not specifically shown as circles will have to be estimated along the flightline. You can find out more about using index maps here.
Q. I've found the location of an air photo I'm interested in on one of the index maps, and I've figured out its roll and frame designation - I know its vintage will be within the range of years specified in the map label, but how do I know exactly which year it's from?
A. Click on the 'Year/Filmroll Correlation Listing' link and find the filmroll, or look it up here.
Q. I've checked out 'Search Air photos' and the index maps - are there still more air photos?
A. Yes. There are an additional quarter million air photos taken between 1950 and 1989 designatead as 'site-specific' operations that are only recorded on the original paper maps. A future update will include tools for locating air photos from these operations. If you think there may be a site specific operation for your area of interest you can contact GeoBC - someone will help you to deteremine if such an operation exists.
Orthophoto Search Questions
Q. How do I view inforamtion about an orthophoto in Google Earth?
A. Click the blue disk icon on top of an orthophoto centre to view information about that orthophoto. Click on the image thumbnail in the information window to display a 1/16th scale version of the full-resolution orthophoto, which you may freely print or download from your browser window. If the full-resolution orthophoto is available for purchase, an Add to Cart button will be displayed below the orthophoto details.
Q. Why are there no low-resolution thumbnails for some orthophotos?
A. Some images in GeoBC's orthophoto collection are not owned by the Province of BC. GeoBC is not permitted to provide low-resolution thumbnails of these images.
Q. Why aren't there any orthophotos from before 1995?
A. 1995 was the first year that digital orthophotos were produced. Orthophotos from earlier years existed only as hardcopy photos or mylar overlays. These are no longer available.
Q. Why are there no orthophotos for some areas of British Columbia?
A. In recent years, orthophotos have normally been produced from all Provincial air photo acquisition. Before 2006, orthophotos were typically only produced for between 50 and 60% of the annual air photo acquisition. For some areas of British Columbia, notably the north west corner of the province, parts of Vancouver Island and some parts of the South Coast, no new aerial photography has been acquired since the mid 90's, when digital orthophotos first began to be produced.
Q. Can I download and view or print the low-resolution image without purchasing the full-resolution version?
A. Yes. The low-resolution orthophoto images are free for personal use, although they remain the copyrighted property of the Province of British Columbia. For commercial use, or for inclusion in published material you will need to get permission.
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