Hi,

I have two questions regardin the algorithm which is used for calculating the cost_distance values in the 'Path Distance' tool. As it is described in its help page, cost-distance calculation follows the formula:

Cost-Distance = cost-surface*surface-distance*([friction a * Horizontal Factor a + Friction b* Horizontal Factor b]/2)* vertical factor

which is multiplied by 1.4 in case of diagonal movement from cell to cell.

1- what happens if we do not define any Vertical Factor in the tool? what is the default value which would be assigned to it?

when it comes to calculate the accumulated-cost it uses the following formula:

accumulated-cost-distnace= a1+ surface-distance*([friction b* Horizontal Factor b + Friction c* Horizontal Factor c]/2)* vertical factor, and my next question is :

2-why it doesn't use the "Cost-Surface" term in this step anymore? doesn't it really follow the same concep as the previous formula to calculate the cost of movement to proceed to the next cells or is there any other explanation for it?

Thank you in advance for your help,

Regards,

Sima

I have two questions regardin the algorithm which is used for calculating the cost_distance values in the 'Path Distance' tool. As it is described in its help page, cost-distance calculation follows the formula:

Cost-Distance = cost-surface*surface-distance*([friction a * Horizontal Factor a + Friction b* Horizontal Factor b]/2)* vertical factor

which is multiplied by 1.4 in case of diagonal movement from cell to cell.

1- what happens if we do not define any Vertical Factor in the tool? what is the default value which would be assigned to it?

when it comes to calculate the accumulated-cost it uses the following formula:

accumulated-cost-distnace= a1+ surface-distance*([friction b* Horizontal Factor b + Friction c* Horizontal Factor c]/2)* vertical factor, and my next question is :

2-why it doesn't use the "Cost-Surface" term in this step anymore? doesn't it really follow the same concep as the previous formula to calculate the cost of movement to proceed to the next cells or is there any other explanation for it?

Thank you in advance for your help,

Regards,

Sima

The right formula is:

Accum_cost_distance = a1 + Cost_Surface(bc) * Surface_distance(bc) *

{[Friction(b) * Horizontal_factor(b) +

Friction(c) * Horizontal_factor(c)]/2} *

Vertical_factor(bc)

This has been corrected for the 10.1 documentation, please see: How the path distance tools work.

If no vertical factor is set then the vertical factor will have no effect on the output.

Thanks

Pavan