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7

There is no way to get floor heights from a lidar pointcloud. Lidar is captured by bouncing lasers off the groundsurface and measuring the bounced back pulses. Therefore there is no way for the lasers to 'see' through the roof of a building and return a floor height. However, a solution to this may be to classify your las point cloud into ground and non ...


7

Erdas used to work together wih ESRI, but now it is ENVI that has joint its forces. I would therefore use ENVI for the compatibility. But if you are looking for an good open source solution, I recommend Orfeo Toolbox (http://orfeo-toolbox.org/otb/ ). You can either use the library, the command line application or a complete GUI (called Monteverdi). ...


4

There is nothing built into the software that can solve differential equations. I am assuming that your values are derived from spatial data or you would be posting this on another site. Your best bet (if you are tied to one of these software packages) is to write some code in ArcPy that pulls in your values and does the math. The NumPy Python library, ...


4

Though I am not able to understand the difference between the standard deviation output and the percentage output and what is the significance of using one over the other? Those refer to the threshold used to decide whether there has been any change between two images. For percentage change, it uses a symmetric relative difference formula to ...


4

From the USGS FAQ: the blue band is useful for "Bathymetric mapping, distinguishing soil from vegetation and deciduous from coniferous vegetation". It's my experience that you get better results by using band combination, however.


4

ENVI has never been very good with formats other than the native bil and tif. I have seen the behavior you mention, but it is inconstant and dependent on how the file was saved into an img format. It would be good to know how you are saving the file. I find it very unstable to just give output an img file extension. Your best bet is use the "Save File as ...


4

You can find the system requirements for ArcGIS 10.2 (the latest version) here and for ERDAS here. The laptop you list more than satisfies the minimum requirements. For schooling you probably won't need a powerhouse and the machine you list will be more than adequate. In the event that you want to upgrade here are some things to consider: Processor: an ...


3

For specific remote sensing tasks you could check out BEAM. If you are not afraid of command line, I would suggest a combination of GRASS (for storage and datahandling and analysis), QGIS(for visualization) and GDAL/OGR and pktools (for analysis). All these are open-source. A very good instructional site is here.


3

Penn State offers a wide variety of free online classes (for no course credit). You can take a look at the Penn State Online Geospatial Education Program Class Calendar. From there you may want to take a look at: Geog 883: Remote Sensing and Image Analysis and Applications: An intermediate-level course focusing on the use of remotely sensed imagery in ...


3

I assume you are interested in generalizing your supervised classification. You can achieve a similar result using the ArcGIS Majority Filter (Spatial Analyst) tool. Using Erdas, the Sieve tool is located in the Raster tab > Thematic (Raster GIS group) > Sieve A widely accepted approach is to use GDAL's gdal_sieve.py, describes as follows: The ...


3

I would recommend calculating soil moisture indices from Landsat TM bands. MTRI has an interesting article on creating soil moisture index (SMI) from Landsat TM 5. Also, I would recommend exploring soil moisture estimates using TM band 6 (Thermal IR). Attached is a good tutorial on calculating indices from Landsat TM bands using ArcGIS 9.x (as you ...


2

you can check out Qgis Sextante Toolbox in plugins repository. it has lots of geoprocessing alagorithm in it. SEXTANTE is a spatial data analysis library and a powerful geoprocessing framework.The main aim of SEXTANTE is to provide a platform for the easy implementation, deployment and usage of rich geoprocessing functionality. It currently ...


2

You can open the raster image as a GDALDataset : poDataset = (GDALDataset *) GDALOpen( pszFilename, GA_ReadOnly ); Then get the raster band containing the color codes with : GDALRasterBand *poBand; poBand = poDataset->GetRasterBand( i ); where "i" represents the raster band id. Then iterate over the raster band pixels and read each pixel color code value ...


2

If you have gdal command line setup you can try this: gdal_translate -outsize xsize[%] ysize[%] <src_dataset> <dest_dataset> Example: creating 25% of original image. gdal_translate -otusize 25% 25% input.tif output.tif ......


2

There are several good sources including the following: WELD WELD generates 30-meter composites of Landsat 7 Enhanced Thematic Mapper Plus (ETM+) terrain corrected (Level 1T) mosaics at weekly, monthly, seasonal and annual periods for the conterminous United States (CONUS) and Alaska. These mosaics provide consistent data that can be used to ...


2

GRASS GIS (open source, since version 6 with a new graphical user interface) offers many image processing methods including: Import of all common satellite, aerial and UAV data formats Preprocessing Geometric preprocessing/Georectification Radiometric preprocessing Correction for atmospheric effects Correction for topographic/terrain effects Cloud ...


2

I have an "older" 2011 HP with the specs show below. Consider this as a baseline for work with Erdas and ArcGIS 10.2. In other words, do not go with a system with less capability than this one as the lack of performance will likely be noticeable. Realistically, any heavy geoprocessing you do is often on a school computer or a via VPN connection to a ...


2

The overall hardware specs should be more than sufficient for basic tasks. However, note that the display's vertical resolution of 900 pixels can be quite limiting during work with maps or satellite / aerial images. You could consider a notebook with higher resolution, e.g. a 1920x1080 display or similar. At least I recommend to do a hands-on-comparison of ...


2

with ArcGIS, you can use the "copy raster" tools to convert the img file in a ENVI file. Just write ".dat" at the end of the name of the output file. With ENVI you just need to convert to an ENVI file and use the file that has no extension. By the way, you don't need to write code to use gdal. You can install it with OSGEO4W, then you type gdal_translate ...


1

Actually, I have had some good experience displaying images with QGIS. And you can play with transparency. But from what I know you cannot have two linked viewers. You have other free open source softwares (Monteverdi, BEAM ), but often those for raster image processing do not provide multi-image viewers. They are however quite fast to display your image ...


1

Idrisi - not free but cheap and there is a free trial version. Good for raster comparison and change direction. http://www.clarklabs.org Or saga! Not simple but very powerful and free! http://www.saga-gis.org/


1

If you're new to remote sensing, I would recommend a couple books that are standard for beginners in the field. Remote Sensing and Image Interpretation - Lillesand, Kiefer, Chipman Remote Sensing of the Environment - Jensen These books are a great introduction to RS and will be infinitely more valuable than software tutorials for those who do not yet ...


1

You can do it by this way: 1. Go to 'Image Interpreter >>> Utilities >>> Change detection'. 2. Give before and after images. 3. It will produce the 'Difference' image as well as 'thematic image' of five classes namely decreased, some decreased, unchanged, some increase and increased. From which you can calculate the size of your decreased, increased and ...


1

I'm not a user of ERDAS software, but i'm wondering if you could use any of these datasets to help you distinguish particular features in the coastal environment you're working on? I've found the GSHHG dataset a useful tool in the past.


1

You could use Fledermaus: http://geotools.csc.noaa.gov/program/Previous%20Programs/presentations/GeoTools%20pdfs/F13%20Lockhart.pdf, it may help you. In case you want to tune finely in order to enhance details, a good software for that is GMT (Generic Mapping Tools): http://www.lidarnews.com/content/view/8970/136/, this one is quite powerful but the learning ...


1

I think you have a collision in lmgrd process ports. If you edit the licence file in a text editor, you can change the default port that is used by the lmgrd process that uses the licence file. The licence file looks something like this: -------------- START_LICENSE SERVER 192.168.1.15 ESRI_SENTINEL_KEY=some_number_here 27006 Note the port used in this ...


1

Here are the steps on how to do it in ArcGIS (Extract from online help) In ArcMap, click the Add Data button. Navigate to the location of the HDF file. Click the file and click Add. The Subdataset Selection dialog box opens. Click a single subdataset to add. Optionally, press and hold the CTRL key to select more than one. If you choose more than one item, ...


1

I would try something like the following as a loose workflow: a) buffer around the points (arcmap has a flat option to get 1km^2). b) merge those into a single feature class to overlay on the whole map. c) use the results from a) to clip tiles from the NLDS to find the data present. d) compile the results from c). e) compare results from d) to the whole ...


1

I would download the data again. Sometimes large downloads get corrupted. I have downloaded this exact data so I know that it is fine. You should not be getting any errors while unzipping. The ige file is just an indexing file to address large files that exceed 32bit addressing space. The file that you work with is the img. I would recommend subsetting the ...


1

In ArcGIS you can clip the raster(img file) using a graphic. If you have a polygon layer that you want to use as the clip boundary right click on it and convert feature to graphic. Make sure the resulting graphic is selected and then right click on the raster. You should be able to export and use the graphic to clip. If its not part of the export on raster ...



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