Frequently Asked Questions



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What do you need to download a satellite image?

Conabio offers satellite images at no cost whatsoever. You only have to register in the visitors´ book. The link for the visitors´ book is in the left-side green margin.

In what software program can images be opened?

Files obtained by FTP are binary files and can be imported into satellite-image processing systems or by Geographic Information System software. Among those are:

Erdas imagine

PCI Geomatic

ENVI

ERMAPPER

Arc/Info

IDRISI

GRASS

SPANS

…among others

Due to the fact files correspond to a satellite image, they cannot be opened by design programs such as:

Microsoft Photo Editor

Imaging for Windows

Photoshop

PhotoPaint

PaintShopPro

…etc.

What images can I get?

Conabio offers the public only satellite images from AVHRR and MODIS sensors over the past 30 days. Therefore, the oldest file date will be replaced by most recent file date. Therefore, images from earlier dates are not available.

What is a satellite image?

It is a pictorial representation measuring the electromagnetic energy recorded by a sensor, not by photography. A photograph is normally taken within a certain spectral range (visible light). Satellites take images outside this limited range.

What is an AVHRR satellite image?

These images are recorded by an Advanced Very High Resolution Radiometer sensor found on-board NOAA satellites. At present, the NOAA12, NOAA15, NOAA16 and NOAA17 satellites are active.

Characteristics:

Spatial resolution: 1.1 km

Spectral resolution:

Channel	Spectral region	Wavelength (m m)	Spatial resolution (m)
1	Visible	0.58 – 0.68	1100
2	Near infrared	0.725 – 1.10	1100
3	Medium infrared	3.55 – 3.93	1100
4	Thermal infrared	10.3 – 11.3	1100
5	Thermal infrared	11.5 – 12.5	1100

Temporal resolution: Daily (12-13:00). Generally, two passes are required to cover Mexico. Therefore, a mosaic is made showing a single image of the entire country.

What is a MODIS satellite image?

These images are recorded by a Moderate Resolution Imaging Spectroradiometer sensor on-board Terra-1 and Aqua-1 satellites.

Characteristics:

Spatial resolution: An image has three resolutions, two 250-meter channels, five 500-meter channels, and the rest 1000 meters.

Spectral resolution:

Channel	Spectral region	Wavelength (µ µ)	Spatial resolution (m)
1	Visible	0.620 – 0.670	250
2	Near infrared	0.841 – 0.876	250
3	Visible	0.459 – 0.479	500
4	Visible	0.545 – 0.565	500
5	Near infrared	1.230 – 1.250	500
6	Near infrared	1.628 – 1.652	500
7	Near infrared	2.105 – 2.155	500
8	Visible	0.405 – 0.420	1000
9	Visible	0.438 – 0.448	1000
10	Visible	0.483 – 0.493	1000
11	Visible	0.526 – 0.536	1000
12	Visible	0.546 – 0.556	1000
13*	Visible	0.662 – 0.672	1000
14*	Visible	0.673 – 0.683	1000
15	Visible	0.743 – 0.753	1000
16	Near infrared	0.862 – 0.877	1000
17	Near infrared	0.890 – 0.920	1000
18	Near infrared	0.931 – 0.941	1000
19	Near infrared	0.915 – 0.965	1000
20	Medium infrared	3.660 – 3.840	1000
21	Medium infrared	3.929 – 3.989	1000
22	Medium infrared	3.929 – 3.989	1000
23	Medium infrared	4.020 – 4.080	1000
24	Medium infrared	4.433 – 4.498	1000
25	Medium infrared	4.482 – 4.589	1000
26	Near infrared	1.360 – 1.390	1000
27	Thermal infrared	6.535 – 6.895	1000
28	Thermal infrared	7.175 – 7.475	1000
29	Thermal infrared	8.400 – 8.700	1000
30	Thermal infrared	9.580 – 9.880	1000
31	Thermal infrared	10.780 – 11.280	1000
32	Thermal infrared	11.770 – 12.270	1000
33	Thermal infrared	13.185 – 13.485	1000
34	Thermal infrared	13.485 – 13.785	1000
35	Thermal infrared	13.785 – 14.085	1000
36	Thermal infrared	14.085 – 14.385	1000

The sensor had problems in channels 13 and 14, so that the they are not included in the image.

Temporal resolution: In order to cover all of Mexico, three satellite passes are needed. We can see, therefore, that the entire country is not covered in a single image.

For doubts, questions or comments
Remote Sensing Area