Frequently Asked Questions

Question 1: How can i get satellite imagery?
Question 2: What is the highest satellite imagery detail as a commercial product?
Question 3: What is the accepted map scale derived from highest resolution satellite images?
Question 4: What does orthorectification means?
Question 5: What are the differences between optic and radar images?
Question 6: What are the criterias we must pay attention on satellite images?
Question 7: What does SLC-Off mode mean in Landsat images?
Question 8: What is SRTM data?
Question 9: Which satellites take night images?

Question 1: How can i get satellite imagery?

Answer: Fist you have to define the location of region of interest (ROI) by giving information like name, coordinates etc. You must define the datum and projection of your coordinates clearly for better and correct results. After searching the image databases according to the criterias you define, we first send you the results as quicklooks of the founded images according to your ROI and also the acquisition dates and the meta informations (cloud ratio, nadir angle, quality etc.). If the images fill your needs then the request forms are sent to you. If there are no images in archives for the interested region, then the conditions for new acquisition and programming of the satellite will be informed to you soon.

Question 2: What is the highest satellite imagery detail as a commercial product?

Answer: The highest satellite imagery as commercial is WorldView-3 nowadays with 0.30cm spatial resolution as pansharpened image.

Question 3: What is the accepted map scale derived from highest resolution satellite images?

Answer: The accepted map scale derived from highest resolution satellite images is accepted as 1:5000 map scale.

Question 4: What does orthorectification means?

Answer: Orthorectification is the process by which the geometric distortions of the image are modeled and accounted for, resulting in a planimetricly correct image. To put it another way, our 3D world is imaged by most sensors in 2D and orthorectification corrects for many of the anomalies resultant from this conversion. Orthorectified imagery is particularly useful in areas of the world with exacerbated terrain features such as mountains, plateaus, etc.

Question 5: What are the differences between optic and radar images?

Answer: Radar satellites send their own signal and get back the data by its signal. These signals never gets affected from rain,cloud or night. They can take images in any condition day or night except in some special conditions. But optic satellites use sun light and only take images in day time in good weather conditions.

Question 6: What are the criterias we must pay attention on satellite images?

Answer: There are 5 different conditions in satellite images. These are; spatial resolution, radiometric resolution, spectral resolution, temporal resolution and swath width. Spatial resolution is the the size of a pixel that is recorded in a raster image - typically pixels may correspond to square areas ranging in side length from 1 to 1,000 meters. Radiometric resolution is the number of different intensities of radiation the sensor is able to distinguish. Typically, this ranges from 8 to 14 bits, corresponding to 256 levels of the gray scale and up to 16,384 intensities or "shades" of color, in each band. Spectral resolution is the number of different frequency bands recorded - usually, this is equivalent to the number of sensors carried by the platform(s) due to spectrum. Temporal resolution is the frequency of flyovers by the satellite or plane, and is only relevant in time-series studies or those requiring an averaged or mosaic image as in deforesting monitoring. Swath width is the area width of the satellite scan in one pass.

Question 7: What does SLC-Off mode mean in Landsat images?

Answer: Landsat-7 ETM has come across with some problems in image after 2003. These unusable parts in the images are beğing replaced by old acquisition images. These images are called as SLC-OFF mode images.

Question 8: What is SRTM data?

Answer: The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000.

Question 9: Which satellites take night images?

Answer: Radar imagery is most probably preferred in night acquisition images.