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Hi, I downloaded an example from ESRI website about using hotspot to analysis crashes data. I took a close look about Model builder - Model 1 Create Network Weight Matrix and run this model and then using the script "Convert Spatial Weights Matrix to Table" to see spatial weights."INVERSE" is chosen to be a parameter in Conceptualization of Spatial Relationships, that's mean features farther away have a smaller weight than features nearby. However, it really makes me confused. For example, I found two points are very closed,but the weight is not bigger. I attach the screenshot for reference. Such as, Unique_ID = 6810,6812,6809. Three points are very closed, but weight is small. [ATTACH=CONFIG]14035[/ATTACH] So could you someone help me understand this processing? Thanks so much in advance. Wei
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05-02-2012
02:20 PM
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I think I met similar situation, I use spatial join to do count point on line! I need to count the number of points on an LRS polyline. Seems like this should be simple but I can't figure out a way to do it. I've got a road network layer and crash layer. The crashes were mapped as events on the LRS and saved as a new feature class. I am using a seperate dataset to segment the LRS network, and then I need to be able to count how many crashes occur on each segment. Thanks
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12-13-2011
01:32 PM
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Hello, everyone I am going to use hot spot toolbox in ArcGIS 9.2 to analysis and locate the high collision location. I list the step what I did. Then I struck inside. 1. Spatial join point (collision data) and polyline (Street Network), get collision count for each segment. 2. Calculate collision rate according to segment legth and traffic volume and count of collision. 3. Already use Moran's I index to judge collision point is spatial cluster, then I choose the appropriate distance band. 4. Using Hot Spot toolbox, and choose collision rate to be an input field.But I didn't get the statisfy result. Anyone can help me out of my struggle. Thanks
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12-13-2011
01:28 PM
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We aren using the method 2 and method 3. If no (X,Y) or (Latitude, Longitude), just using the address locator to geo code the collision point. I was wondering what other cities/counties, etc are doing for traffic collision mapping of accidents. I have noticed their are three basic schools of thought on how to collect the data, they are: 1. Snap the accident point to the nearest intersection. 2. Have police officers take Latitude/Longitude at the point of the accident. 3. Record them as Primary Street and Distance from Cross Street. We currently use method 3, they are entered by a police officer into an Access database. The database has fields for "at intersection" true/false, �??distance�?� from intersection in feet and �??direction�?� from intersection. We export out a table and run an Avenue code that will place the points. If it is at the intersection a point is placed where the street centerline crosses. If it is a distance from the intersection the point is placed on the �??primary�?� street a certain distance and direction (N,E,S,W) from the intersection on the �??secondary street�?� . I'm trying to find a modern way to do this. I am not a python expert, so I haven't had luck doing it that way. I was even thinking of designing a flex app and giving the police officers access to it to place their points. What method are you using?
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12-13-2011
01:11 PM
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